Many Space heater adds yammer "3 times more efficient" or some such fecal matter.
Fact is all electric space heaters are exactly 100% efficient that's because all losses are HEAT.
Since you want Small I Recommend a ceramic
Second: RV wiring may not be up to 1500 watt. 750 is not often a problem but 1500 is.. the reason is the el-cheapo "uni-box" style outlets do not have enough contact area with the wires so they get hot and literally melt.
I put in a pair (over time 3) Heavy duty 15/20 amp outlets 12 ga wire and each with a circuit breaker all to itself.. No problems. 12ga wire bent around a screw beats 14 ga "punched down" every time.
