I have used about every heater out there in my RV's from my motorhomes/fifth wheels/travel trailers and truck campers...
Without a doubt the infrared heaters put out more heat than any of the others in an RV...Not even close...When we bought out house it included a Sun infrared heater.Amazing how it heated 1300 SF in normal temps here.
In a 30ft travel trailer it heated great down to the teens.To big for a TC so I lent it to my son who heats his smallish house with it untill it gets really cold...
Next would be the milk house heater..Just does a great job period for a 1500 watt electric heater but the infrared blows air like no other 1500 watt heater.
It just works, no matter what others say about wattage etc, from my use in Idaho in the winter and I have tried them all.