Interesting idea. I didn't even know you could buy an HVAC unit for doghouses, but here's a used one that was used in a teardrop camper [on Austin, TX craigslist.
Carlyle tried a similar approach : http://www.expeditionportal.com/forum/showpost.php?p=163393&postcount=57
The AC is a Little Guy Trailer ac and looks like it is an adapted dog kennel ac of all things. Works great and minimal draw on the battery bank.
A couple came today during the load, took one look at it and ordered one for their Alaskan.
The air conditioner system works great! When hot out you need to turn it on early as it takes a long time to actually cool rather than just keep up with the inside temp when it's 100+ degrees outside.