Our roof will not support a traditional air unit, they do make an RV side wall unit made to take the shaking of a trailer ride. Problem is you need 120v and lot of it.
Thinking of getting a HD locking boat cooler mount a little rad (heater core) on top of wall inside seat area with low amp 12v fan on one side to blow into trailer, add intake air piping to back of fan, plus a 12v pump at floor below. Connect pump through lid into cooler full of water and ice block in cooler, piping up out through pump to rad out back into cooler to cool trailer. With grills and have tubing to cooler and pump use quick connects it would be easier to fill cooler. Pump could be on floor of trailer like the water pump under sink.
to run this would work at a wilderness site. Block ice, cubes or crushed would work in cooler. Also could have a bypass water hookups for connecting to a cold stream with an input water filter.
Quick connects would help in this optional stream hookup.
12v AC sounds good, any ideas for possible improvements?
project will be a go just want to get ideas to refine and avoid possible problems in advance.