We had the dealer replace our bathroom fan with a Vortex fan when we bought our 213. Except for a few hot nights when we opted for A/C, we ran the Vortex fan every night with the bathroom door closed and the windows on the rear slide open. The Vortex fan pulls a lot of air through the camper from under the 2" opening below the bathroom door. Never had a hint of condensation with night temps varying from 70 to mid 40's. I also installed a MaxxAir cover over the bathroom vent so I could run the fan without fear of rain getting in.
John, Heidi, with Big Papi & Venus (Cocker Spaniels)
2012 Nissan Pathfinder SV 4X4
Hensley Cub WDH, Tekonsha Primus IQ