All right. This thread just made my decision. I've been milling this idea over and over, torturing myself. I'm doing it. You can find cheap, older, pop ups on Craigs all day long.
I'm buying one, making a longer, stouter frame, putting real springs under it, putting matching tires to my truck on it, and using the snot out of it.
I'm quite sure the $15k+ I don't spend on a true "offroad" trailer will buy lots of gas for my adventures. And the satisfaction of re-designing/building it myself will go a long way too.
Thanks for the final nudge I needed.