You can't go on forever without rest, the mechanic allows an easy way of forcing the party to rest without resorting to counting hours or applying fatigue rules. Sure, move fast, but not recklessly... like the party did and almost got wiped. I disagree about the DM adjusting the encounters to accommodate the party's bad decision. What is the point of the game if your decisions don't matter? If you make a mistake, things should go poorly.

You have several options, but it sounds like what you want is a permanent change in the groups behaviors. That sir, is well within your capability. My best advice is that when you need to make a point with a group that is set in there ways, do not be subtle or clever about it. Drop it like an anvil and then drop it again and again until they start to listen. Not just hear your words but genuinely listen.

State your case honestly and clearly to the GM. State how this is important to your enjoyment of the game and the meat grinder mechanics aren't fulfilling what you need to have fun with your game. The GM will be painfully aware of people judging his value as a story teller. This is a game of you being able to convince him that he can tell a better, more compelling story if he's willing to step outside his comfort zone and try something new. IF the GM is licked inside a ball of insecurities then this may only lead to frustration, but will give you an accurate assessment of his willingness to adapt.

Try and gauge the where the other players stand on the issue. If they don't share your views specifically, try and find out what they would like to change to improve their enjoyment of the game. If your GM turns out to be the adaptable sort, then this is a great way to build up bridges of communication and get people to start giving feedback for the continual improvement of your games. People are multifaceted beings apt to change over time, a good group will build up communication to meet the needs of that change.

If your group wants change and your GM isn't playing ball, its time to hijack the game. So long as the players act in the scope of what a D&D party could physically accomplish (such as not going super saijin and punching out the moon) you can get away with murder. Be outlandish, high energy ans lots of fun. The goal is to be the combined front of near unstoppable high energy hijinks. This will put any GM in their place that if they aren't willing to make the game suit the needs of the players, those players will do it anyway.

If you can talk to your players about the changes they would like to see, your GM is unadaptable, and you are willing to GM, then replace him. A player willing to GM and do it better end the problem of a tyrant GM like an eight foot tall axe man named Chop-Chop the Executioner. Once the players have seen better, the old GM might get one chance at proving themselves if the group is feeling generous.

TL;DR You are willing to a adapt in a group that might not. That alone gives you all the power to change the situation to your liking. Roll up your sleeves and be willing to get messy. A little diplomacy goes a long way to having fun at the gaming table.

Less than helpful advice:
When you die again reroll as a witch?

I think probably the party likes playing the way they do and thus will resist change from the newcomer to modify it. I'd view it more as a beer and pretzels game than anything and just go with the flow. If that's not fun for me then I'd find a different group.

Yeah, you can ask and see if they want to change, but a lot of times the group plays a certain way because that is how they like to play. I've had "funny talkers" try to convince me it is fun but mostly they annoyed the group and ended up having a terrible time. If they like playing the tabletop version Diablo, they are unlikely to turn into sit around and tell a story players. You can see if they are open to change, but if not you are better off moving on than trying to convince them to quit playing the way they enjoy playing.

I'd just drop the cleric and play what I wanted, at that point. If healing doesn't matter and death's just an inconvenience, I really don't care if the rest of the party survives.

If death is just an inconvenience let em die, and get rich off their corpses

Except I found out how he blocks that amassing of wealth.

When everyone levels up (and switches to the next adventure path), he sets our amount of wealth per party member to however much we should have at that level... so at level 2, we each have 1000 GP, including the value of all things we're carrying at that point. To keep an enchanted ring the party found, we had to put a total of 1200 gold from our collective "wealth" into it.

Anyway, starting with the next session, if the players are stupid enough to rush headlong into battle when the healing's spent, ol' Kismet Prime is gonna wander off from the party and find a place to rest safely while the rest of party commits suicide.

Side note: I'm really going to make this Cleric go full turtle as he progresses, I think. I was just working on his level 3 character sheet in case we get that far in the game, and when I saw the amount he had to spend (3k GP), I went ahead and grabbed enchanted +1 shields and armor and left the rest of his equipment exactly the same, which puts his AC at 20 despite having a Dex of 10. Also, I'm working on RPing in that this character has a cowardly streak, after his first adventuring party was killed by wolves, and he himself almost died at the hands (well, teeth) of a Warg.

OK, either your GM is the most painfully literal minded individual that I have ever heard of, or he wants this to be a purely tactical exercise and is doing his best to off-load all the work on the players. I'm not sure whether I'm more surprised at the way he does things or that he's managed to form a group of regulars.

You can rest when you're dead.

That's silly, blocking amassing of wealth through artificial means is well not stupid but it can be possible to stop wealth amassing if you do other things than imposing the books on people.

I wonder though if that was the GM originally or how much of it is actually the players. If they hated death being a big deal and simply getting rich off their dead then the GM might have imposed that cap to prevent all kinds of shenanigans to get rich quick by offing each other.