Doing without propane

Look up portable IH cooker.

Of course youll also need power suply to use it,such as Jackerry or Bluetti rechargable generator.
I see many rvers using just that.
Example

https://youtu.be/6KgW7OQDsTk


https://youtu.be/VAhbMuXScqc

Not that I can think of unless you install a little wood burner and heat with wood or have enough battery capacity to heat that way which would be very expensive.
You the guy with the rusted out LP tank?
Have you considered a storage area in the RV that you could modify to accept 20lb or 30lb portable LP bottles? Basically just needs to be sealed from the interior with open air ventilation. Piping and hoses shouldn't be too much of a challenge.

Another option that would use electricity, but near as much as electric heat could be a pellet stove? Quick check, saw a wall mount pellet stove that was 27x36 x 12" deep. Heats 1000sf, so you could run it very low to heat a couple hundred sf?

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?

IH cooker looks interesting but no good for dry camping. Right now my onan gen is no good so no genset either. Depending on the weather maybe I would not need a heater on some nights with this global warming. I do camp between Dec and March only. But only in very southern desert country. Doug

No, your options are really just propane. You can use the 1lb cans for a buddy heater or similar, or use the 20lb bbq tanks that fit your RV. Make the 20lb tank happen.
You need batteries for boondocking multiple days and also solar. solar is fine in southern states in the winter depending on your needs. It works for me even in the forest, which of course is leafless in winter.

Two golf cart batteries are a good investment and are more robust than the marine battery.
The lithium batteries are low enough price that if you camp a lot it can be worth the investment assuming you will stay with it 5-10 years.

Again, solar. Do not get the flexible panels, glass only. 200-400 watts is typical, and an MPPT controller that fits the system. Go 24 volt and let the controller change it to 12. By going 24 you use smaller wire from the panels to the inside controller and the controller is always supplied more than 14 volts. This is running two panels in series. Panels are 18 volts, so thats really 36 volts in series, but it is still called 24 volts. dont try to understand this.

How do you carry and connect the portable lp tank to the inside heater safely? Solar I will look into. Does not solar compromise roof integrity? Doug

Brownleaf wrote:
How do you carry and connect the portable lp tank to the inside heater safely? Solar I will look into. Does not solar compromise roof integrity? Doug

High pressure propane needs to stay out of the living space. Need a regulator to drop the pressure and connect to the existing main distribution line.

Solar is fine on a good roof.

If you have an alternative for cooking (like an electric cooktop or small propane bottles), there are gasoline or diesel powered heaters that can heat your RV.

Webasto is one popular brand.

Eberspacher is another brand.

But it's not a cheap solution, figure around $1500 - $2000 for the heater, plus installation.

Brownleaf wrote:
How do you carry and connect the portable lp tank to the inside heater safely? Solar I will look into. Does not solar compromise roof integrity? Doug

If that is a question, scratch my ideas.
Big Buddy heater and a 20lb bottle it is. No assembly required. You’ll have to deal with condensation though.
Solar ain’t gonna cut it without much more expensive and technical additions than plumbing in a LP bottle.

If you are boondocking, likely nothing that will be simpler and cheaper than just fixing the propane tank problem.

If you are in a formal campground with power and it's not really cold, a space heater carefully set up, it an option.