Are you in a situation where you have an under-floor propane tank that is bad and need expensive replacement so now is the time to ask this question?
OR new bbq tank for $40 full?
Keep the propane onboard for the heat, that furnace is so easy and already safe.
Use the stove, it is already there, yes it takes a little longer, but no need to run a generator. If you like cranking a generator to heat a plate then fine too.
The Buddy heater will be maxed out for a 24 foot camper, but use at night in a closed bedroom with window cracked for safety and a CO alarm you will be fine.
Buddy does put out humidity so room will be more humid and you will get condensation on walls that can lead to mold if used a lot.
If you were building from scratch it is one thing, but you have an RV built for propane, use it. what about the fridge, you don use a fridge?