A 2000 watt will not run most A/C units because they surge up to or above the max on start up. I have a Coleman Polar Cub RV style roof mounted unit that requires only 1100 watts to run but surges above 2000. The Polar Cub is 9500 BTU and IMO is the smallest practical unit for a truck. I run it with a Honda EU3000IS gen set that's frame mounted like an APU. It runs about 14 hours on a 3.4 gal tank of gas and I carry a 5 gal can with me in a frame mounted box. It is not CARB compliant, but I have never been and seriously doubt that I'll ever be hassled when running it. It runs so quiet that unless there is NO noise close by you cannot hear it and this is never the case in trucking. It is much more quiet than any APU I've ever encountered. The hassle is gassing it up but normally you come across a place where you can pull up to a pump. They make propane conversion kits that are CARB compliant and the 3000 is said to run up to 45 hours on one 20 lb propane tank like you would use on your grill.