We have a 2006 POLAR CUB of about 9200 BTUs. Note that higher BTU units are not put on truck campers because it is _needed_ but because it is cheaper for RV manufacturers to contract for one model for all purposes. In our soft-walled, pop-top camper you could preserve sides of beef ...indefinitely, with our 9200BTU model! (I don't recommend getting the heater strip since it pulls too many amps for the HONDA and thus isn't very flexible - - better to go with a ceramic disc heater with a variable BTU output so you can dial-in what the HONDA can handle).
The big benefit of the POLAR CUB is that we can use the HONDA EU2000i to run it. It is _not_ "Kosher" in the big scheme of things so nobody (in authority) is going to 'recommend' it but the amperage 'works' (...is adequate as long as you can monitor your loads).
Less is usually more and this is a case where this paradigm is born out. Note that it is not without its limitations, though. The reason that "authorities" would not recommend it is that there is little 'margin'. As you go up in altitude the amperage of the HONDA EU2000i falls off until your are at about half the amperage at 10,000 feet as you would have at sea level. There are three sizes of carburetor jets available for my 2006 model but it is not something I would recommend to change in the field and it really won't make any difference in your total available amperage - - use the recommended jet for the altitude of your usual haunts. Luckily, the last thing you usually need above 5,000 feet is air conditioning!
For folks with bigger air conditioners or who want to have a margin of surplus amperage, better to go to a 2500 or 3000 watt generator if you can manage the additional weight and bulk. With the smaller generator you really have to have the equipment to monitor your AC amps being pulled. Otherwise you could end up browning-out your system and damaging equipment.