Living in a van seems like it could decrease your cost of living a lot more than it decreases your quality of life. Getting set up in a van would cost about $12k, so it could pay for itself in a year. Here is a good guide on this.
One could also consider going completely homeless; here is an article by a math student who did that.
This kind of homelessness got me down after a while; I got on a bus to return from viewing another flat that had gone, and ended up on the far side of town because I didn't know when to get off.
Thus spake Eliezer:
It seems that many here might have outlandish ideas for ways of improving our lives. For instance, a recent post advocated installing really bright lights as a way to boost alertness and productivity. We should not adopt such hacks into our dogma until we're pretty sure they work; however, one way of knowing whether a crazy idea works is to try implementing it, and you may have more ideas than you're planning to implement.
So: please post all such lifehack ideas! Even if you haven't tried them, even if they seem unlikely to work. Post them separately, unless some other way would be more appropriate. If you've tried some idea and it hasn't worked, it would be useful to post that too.