We've do air conditioning in our Transit. Seems pretty rare so I'll share what I've learned.
We are running 400ah 24v battery storage with 800 watts of solar (24v) with Victron 3k / Mppt
We looked hard at the split units and the older style window air conditioners but my wife pretty much said hell no to a huge box on the back or the ghetto look of the window unit hanging out the back. We ended up going with a portable because a roof mounted air would have eaten up a lot of solar and our floor plan had ample storage for it. Had we gone with a split we would have been looking at a slight reduction in amps used our portable performs pretty damn good, efficiency would be better but this unit
https://www.amazon.com/Air-Ductless-Conditioner-110-120V-Variable/dp/B01F5Z3JDE is only a few amp hours less than what we have right now.
Comparing power usage is like comparing budgets. Everyone has different needs and what one person thinks is normal another person is a hell no. We wanted to be able to run the air for the entire evening and be comfortable no matter where we were. That goal has been achieved.
We have a Wynter 14k portable. It pulls around 48 amps 24dc when it is running on high. That gives us a little over 7 hours of continuous run time. I don't care where you are or what temp you set the air conditioner at, you are not going to run it non stop all night. So there is plenty of juice to make it through even a very long, hot night plus other DC use.
When we get up, obviously the batteries are on the lower side. Again this varies based on use but we like it cold and comfortable. We have the solar which is really hit or miss on what it replaces. 4 800 watt panels (24v) do a great job of recharging a good chunk of the batteries assuming we have ideal conditions. Then again many times it is cloudy or raining or whatever. So solar isn't reliable unless you are in the desert. Even when we are in FL we see a huge swing in what we get and pollen is a real PIA. Anyway, 1/4 to 1/2 of the battery recharged via solar, maybe less. 15amps@24v alternator charging. So depending on how much you drive that could be a lot or not so much. The rest needs to be replaced with generator use. So 120v @ 30 amps, realistically if you were just charging the batteries you maybe could do all of it but lets say 25 amps 3000 watts / 24v 125ah. Lets cap the charging at 100ah or less. That leaves you using anywhere from 1-2 hours to 4 hours of generator use just to get back to full for the next night.
Hour or two isn't bad. 4 hours plus your regular day power use is a bit long. So it will vary.
Trying to run an air conditioner 24/7 off solar and only solar requires many more panels than you can actually put on a van. The problem isn't running it. You certainly run your air on DC. The problem is you don't have the ability to replace that power through solar nor the space to store the batteries which might allow you to run it for 3 days straight. Just isn't possible in a van with the foot print. You would have to have a solar farm on the land with you to get it done and something like 3 or 4x the number of panels I have on the roof right now and even then you'd still have days where you would need to run the generator a good bit to refill the massive battery bank that now takes up a lot of floor space.