Camco Olympian Heater what size worked for you?

Two wave 3s work great in my 31 ft MH. In 30-50 degree temps, I leave one on low all the time, keeps the chill off at nite. I'll turn it on med and hi during the day whenever we're there.
Depending on where we want the heat, the 2nd heater will come into play. One of the wave 3s is on an 8ft long hose so it can be directed wherever.
When conserving battery power, add another heater before adding fans.