Thanks for the replies everyone! I should mention that I first got the idea from several friends I have of the "dirtbag" variety. One married couple I know lived for 4 years in a truck while working as climbing guides in Yosemite, and another guy I know has lived off and on in his Honda Element so he could spend most of his time fly fishing instead of working to have to pay rent.
That's a pretty long commute. And it's not just the gas money, it's also the wear-and-tear on your car and the hours of your time you spend sitting in it. Have you considered moving closer to your work?
This is probably the most Mustachian thing to do, I know. I didn't get into this commute voluntarily; I own my house and the only job in my field nearby is 48 miles away. I make a lot more there than I could closer to home. Where I live is significantly better quality-of-life and property-value wise too.
Is there a place nearby where you could camp (besides a Walmart parking lot)?
I've looked around, and anywhere I could camp would cost at least $12 a night, pretty much exactly cancelling out any gas savings. No free forest service land or anything, unfortunately.
I mean... so you are saving 100 miles.. that is like 3 gallons of gas? Or < $9.
I would not sleep on a hard bed and have to be smelly and without my coffee the next day for $9. In fact, not being able to make my breakfast and lunch would cost me more than $9.
It's about $12 in my vehicle. Being smelly, hard beds, and no coffee until I get to work are not very big concerns for me. My futon mattress is actually pretty comfortable, even just on the floor! I slept on it for several years before my parents made me get a bed. I never eat breakfast, and lunch is makeable in a truck for me (PB sandwich and banana or equivalent).
Its not something I'd want to do all the time, but it saved a lot of money and was kind of fun. I'd say if you can park in a nice area and don't have anyone waiting for you at home go for it. If you don't like it then just hop in the cab and drive home.
I'm leaning towards giving it a shot. Like you say, if I don't like it I can just drive home.