I like to be fully stocked when we get on the road even when headed home.
I am not sure if this is a helpful reason or not, low center of gravity. I think having 500#s in the lowest place I can put it should help. I have been in some very strong gusty cross winds and even in the windy mountains having a lower center of gravity might be helping.
This being said, I always try to run with empty grey and black tanks because those are on the back of the trailer and I don’t want a heavy back end.
And there is no doubt that wind resistance is the biggest culprit for poor gas mileage. I always drive showing instant mileage, and it sucks in a head wind(pun intended).
2011 Wildwood T26BHXL
2004 Yukon XL Denali
43yrs of camping; one lucky guy