Then you have the smaller opening and the info by billr of his install probably will be of some use.
Do you have the small window just to left of the fridge location?
2016 Tiffin 40 QBH
2015 38RSSA, traded
2005 TK3 #1869, 10 yrs of memories,
2017 F450 KR--one more Ford is it
2009 F450 4x4-died; 2010 F450-retired