It's not a wise move to Have a gas Heater inside a tent, ok.
Having said that.
Sit the gas bottle in a milk crate, or bucket with a wide base.
Helps with the stability factor.
240 V. Fan heater would be better. Access to 240V can be an issue.
Not a Fan of Bar Heaters, they rely on the glow. There's no air movement.
No forced mixing of warm and cold air.
Just Hot air rising by convection, from elements that are extremely HOT!!!
Can be a problem, with something dropping on them, same as gas heaters.
Electric Blankets, maybe, not a fan of them either.
NEVER sleep on a Leccy Blanket with it working, OK.
NEVER FOLD a Leccy Blanket, just roll it up.
The insulation will crack on the elements, wires, if folded a number of times between uses.
The Human body sweats when warm.
The sweat is a really good conductor of electricity.
I don't want to explain the rest, ok.