Have you smoked DMT yourself? I think your question answers itself to anybody who had some quantifiable experience with the molecule
To answer the question direcly, speaking from myexperience: no I don't think hoboxing is a viable way for a prolonged experiences.
It would be probably hard or impossible to achieve desired concentration of vaped freebase DMT in the air, so that you are having psychoactive effect from it and still able to breathe air and your body to function normally in such atmosphere. It's hard to breathe in weed hotbox already, last thing I'd want is for air to be DMT
Also doesn't hotboxing typically involves more than 1 person, to achieve desired effects? So you have several people in a small confined space, tripping balls, some of them inevitably freaking out, some have trouble breathing and wandering outside, some freaking that somebody went outside, etc etc. If there is some courageous group who tried this, I want to read the trip report
There are plenty of existing and better ways to have a prolonged experience (changa, aya).
I'm familiar with Dr. Strassman's work and there is probably a reason why some clever guys sat down, thought about it and went with IV setup for their experiments, instead of a gas mask with DMT vapour (which your hotbox basically tries to be).