I've been told by UHP(got stopped ALL the time in the '85 with the SSR's) that the doors can only be legally removed on vehicles that intended them to come off from the factory, resulting in a 'lip' at the door jamb to keep crap from rolling out. Sounds plausible, but could be one of those interpretations of the guidelines... I never did get ticketed for no doors in the Samurai, or the 4runner. I did however get harrassed that my d-side mirror was too small(i used a 2" stick-on blind spot mirror, sticking out from my tube doors). The UHP said that the mirror has to be no smaller than 4"s in diameter.
Anyways, that's all i know about it... I say run with no doors, or better yet take some time to make some good looking half doors.. way cooler than tube doors IMO.
-Jason