If your Eagle Cap 850 has not the 4 season package, you will burn a lot of propane. I have the same size Lance and it has poor non-summer insulation. No basement, no double pane windows, no extra insulation besides the 1" batting they put in the side walls. What's that? R-6? Nonetheless, we are planning to do a Sept to end of Dec. trip around the boundary states and it will test our resolve to 'rough-it' using gobs of propane to push back the winter. We have camped in the single digits with Cabeza de Vaca, and it can be a challenge. Listen to BKA. Read his full-time TC story. It sounds like you will be moving a lot, which is good to keep up the batteries. And with a gasser, V10 a better winter engine.
Interesting, this very topic is one I posed in December of 2003, just before I joined Club TC here on the forum about a Jan/Feb trip across the northern tier in an 8.5' Lance. We were fresh off a 32 day trip to Alaska that year.
regards, as always, jefe
'01.5 Dodge 2500 4x4, CTD, Qcab, SB, NV5600, 241HD, 4.10's, Dana 70/TruTrac; Dana 80/ TruTrac, Spintec hub conversion, H.D. susp, 315/75R16's on 7.5" and 10" wide steel wheels, Vulcan big line, Warn M15K winch '98 Lance Lite 165s, 8' 6" X-cab, 200w Solar