I was thinking about installing a home type CO2 monitor in my westy
because, though I've never had in problem with everything working
right, I am concerned about surviving in a tight space if something or
everything goes wrong.

With a heater on, there's always the possibility of high CO2. With gas
in any form, there's always the chance of it displacing oxygen in case
of a leak.

Is there a decent low oxygen sensor on the market? Does it not make
more sense to test for the lack of something you need (oxygen) than the
presence of something you don't?

I was wondering if anyone had experience with such.

Jim