Any RV without a Propane Alarm needs a new owner.
A professional grade handheld fuel-gas detector cost me about $125. I used it when plumbing my old farmhouse for a propane stove. The sensitivity is so high that it will trigger on the un-burned gas that escapes as I light the stove, from two rooms away. Far more sensitive than your nose.
A good investment if you have one of these campers.