Allswell, I'm gonna give you one piece of advice which I wish I had before doing it.
I've got an e350 and because of the way that Ford build vehicle bodies, it's pretty hard to get to the little holes between the metal sheets. I decided to use great stuff foam to fill everything up. After like 40 cans and a week I and my wife finished, the stuff is nasty, it sticks everywhere and once dries it'll take days to get out of your skin or hair and it'll never ever come out of clothes.
Now the advice, every time I get in the van and the fan was not running you can smell the foam, it also smells nasty, pretty sure there's a lot off VOC on it and since the area inside is small, the smell releases in no time, we have to keep the fan running constantly which is a pita at night when is cold because we have a propex furnance that we can run more efficiently without the fan pulling the air out, the insulation works pretty well though it can get below freezing and we would be pretty toasty inside .... If I was to do it again, I would choose something voc free or low voc, something like wool would do the trick and have many extra benefits to it, this is the one part in your conversion where you don't want to go cheap, think about air quality since space is small.