We did on our Redwood a few times. I don't see a downside at all, in fact a necessity when traveling through cold regions with water on board. the unfortunate problem is the underfloor is not sealed well, and on the road cold air can pass through faster then the furnace can keep up and you may still get a freeze underneath.
Brad & Dory - Lone Tree, CO
CURRENT - 2013 Itasca Meridian 42E/2013 Wrangler 4dr Sahara
SOLD - 2014 Redwood 36RL/2014 F350 DRW