Do not make the mistakes I made starting with a 36' DP. Did not take very long to realize that there were not enough reasons against getting a longer, nicer coach. I would agree that a Monaco EXE is good choice, but I would go older than 2010... Even back to 2006 with a Detroit engine for2/3rd the price of a 2010. A EXE will have all the goodies as standard, not options. If you are still worried about something more than 40' you can find a 40' EXE with a tag axle which you need so you will have enough CCC.
We boondocks a lot and do not have a problem finding sites big enough for a 42'. Doubt there is any difference in the insulation between HR and Monaco as in the last 10 years they have been built on the same line, assuming ones that are at least 40'