Sub 20' Class C - Ford 5.4L 5 Spd or 6.8L 6 Spd

So I am in the process of buying an Adventurer 19RD former rental up in Canada. Wanted something that can handle the cold and this is the closest thing to a Triple E. The only thing it lacks is the brilliant engine heat ported to the holding tanks (although the furnace heats them).

They have 3 years available: 2016, 2017 and 2018. The latter comes with the 6.8 mated to the 6 speed Torqueshift. The 16/17 have the 5.4 w/5 Speed TS. 350 chassis with single rear wheels.
UVW is just shy of 8000 #'s (with fuel if I recall) and GVWR is 10,500. Doubt I will ever load it that heavy but you know how that goes.
QuadVan will be converting it to 4x4 with taller tires etc. 95% of driving will be on flat land with 5% heading to mountainous resorts. Will NEVER tow anything in the Winter and not very likely in the Summer.

So should I spend the extra 8 grand on the 2018 or will a 5.4 be adequate ?


Fuelly is showing the 5.4 to have a significant advantage for MPG:

***Link Removed***
***Link Removed***

I do take these numbers with a pillar of salt but there are quite a few Class C's included.

I have spent a week reading up on the subject and the waters are even muddier. If only I could get the 3.5 EcoBoost we would be done here !

TIA,
Paul