Ceramic heater preferably with a "tip over switch". Read the labels carefully to see if the heater has a tip over switch.
Rv's are small and these units are usually placed on the floor where it easily can be knocked over.
Which finding one with a safety 'tip over switch' is becoming harder and harder to find since UL caved in and changed the laws and says they are no longer mandatory because lobbyist says its too costly for the manufacturers. :R
I digress IMHO buy a heater with a tip over switch. It tips over and it shuts off immediately.
The new safety functions.....when the heater tips over it will only shut off when it touches something and catches fire to raise the temp level high enough to shut off. A little too late for me.
Off my safety alert soap box. :C