I have a Mr Buddy heater for my camper.
I bought it because it has the low O2 sencer.
It works great.
There is some noise from the propane burner but not lots. Should not spook deer unless they are under your stand, a little wind will cover all the sound .
If you are going to use it a lot in a fixed blind , buy the hose for a 20 lb cylender.
Lots cheaper to run off 20 lb cylinders .