Hello Jeff! The easiest unit to install, and the most dependable in my opinion, would be the Coleman 13.5K BTU model. For more power the 15K model is available. Either of these fine Coleman AC units will do the job for you.
Check out my installation hubs to find these units through Amazon. Those I have ordered through Amazon are usually shipped in 24 hours giving you time to remove the old AC unit.
Good luck and good camping!