Not absolutely critical yet, but I am finally getting ready to do my build. I'm trying to engineer a workable ventilation system WITHOUT a roof vent.
I will wait for your advice, whenever you have the time. I have plenty of other things to work on!
Box van, roof covered in solar, stealth project. So what I'm thinking is to build two ducts out of aluminum (I have access to good scrap and a brake), one each in opposing corner of the box for optimum air change, vented through the floor. The fans will be mounted near the ceiling.
Since a normal FantasticFan will take up too much room, I remembered your side window in your van. I think 2 of the black-hole-forming Noctuas, one pulling in one corner, one pushing out the opposite, may do a fine job. I could just as easily build it to accept 2 in each corner; not sure I'd need to. The van will be insulated to R9 all around.
How well would (2) 160cfm tandem fans work to cool your van?
BTW, I haven't forgotten about the beer I owe you. When this project is done, I'm coming out to pay in full!
If I can haul that much beer, at least