My AC's are in the hatches. If I were still at the stage of choice, I'd keep the hatches useable and move the AC's to the side or some where else. You have a cool bus so you may want to plan your 24'x8' sundeck up on the roof. Maybe NCbob will let you try his "Little Giant"

for getting up thru the hatch. Plus you never know if you'll need the hatrch it for it's original purpose, getting out if the bus is on it's side

,hope not. And if you dont need use it for a sun deck, you'll occasionally find reason to get on the roof
The heat strip on the colmans is a waste of money, I use the little cubes for heating when plugged in.
Also get an AC that has 3 Speed fans with A true low. The coleman "low" is really "medium" and too much for night some times and I think that is also why the haet strrips don't feel warm because the convective cooling from the fans. I take the plastic oscillating fans for sleeping. A heat strip on a unit with a true low speed fan may work but I haven't tried one.
If your in a hurry and can spare the floor space you can try one of these:
http://www.homedepot.com/prel80/HDUS/EN_US/diy_main/pg_diy.jsp?BV_SessionID=@@@@0621018938.1148871444@@@@&BV_EngineID=ccggaddhlldkdlgcgelceffdfgidgio.0&CNTTYPE=PROD_META&CNTKEY=misc/searchResults.jsp&MID=9876&N=2984+4370&pos=n08, and you won't have to build a frame. Maybe drill a hole or stick something in a window try to find aunit that evaporates the condensate whichever you get.
Lot's of good thing you could do, let us know how you work it out.
My opinion only with no warranty or guarantee expicit or implied.