If you have enough insulation to keep the cold in mostly overnight and reduce the running time during the day, I'd say it was easily doable in a super-insulated van.
Bob
If you could get two panels on a van, tiltable would be best. Have enough insulation so that the compressor wouldn't have a 100% duty like mine did today, I think you could do the compressor on, slight draw, compressor off recharge all day long. It would take a lot of battery to make it thru the night though.
If I haven't posted it, this is the specific model I use. It's rated for 446w on high. The reason I suggested the none energy star version for a small generator is he extra 50 or so watts wouldn't make a difference like it does with the solar. Come to think of it, you could buy a small generator for the difference in price.
Now since the window frame in the trailer was never meant to handle the weight of a AC hanging off of it and I don't want to look all ghetto if we go to a dry campground at the lakes, I am considering building a enclosure that will allow air to be drawn in the sides and top, then blown out the center cooling the condenser. In the trailer it will match up to a propped up window but in a van it could match up to a back door window. Replace the glass with a louvered shade and you could run it without it being seen. Well I'd put a shade on both sides and would only believe it would work once I pushed the button but hey, it's a concept.
Many of the factory camper vans I've helped people work on over the years have had a window A/C type unit mounted at floor level in the bottom of a cabinet. They were housed in an aluminum sleeve/duct with an inch or two of clearance on the top and sides, with a drain in the bottom of the duct. On the outside of the van there was only a flat louvered metal panel.