I used to use a heatgun but if you barely get the board too warm, it really stinks. "You don't want to breathe this in"
Now, I normally just use a hammer and 1 inch paint scraper, unless I'm going for specific pieces. Then I use pliers or a flat screwdriver.
You should search on how to make a sandbath, it goes a lot faster than scraping.
Here's some basic information about it,
You "should" be able to use your propane stove to make it aslong as the flame isn't hitting the boards,or it'll make fumes. (I'm guessing this is a small camping stove?) A hotplate might work also. Get a stainless steel cookie sheet and fill it an inch or so with sand and set it ontop.
After the sand is hot, place the board on top and the solder will heat up enough to loosen the components.
Afterwards, take the board and bang it against a bucket and the pieces should fall off into it.
Edit - added