According to your profile YOU have been living in this trailer for several months....so propane cylinders should not be the issue
Purging on those is only required when first purchased (NEW) prior to initial propane fill. After that not needed unless you completely remove OPD Valve exposing inside to air
If it is an Atwood 7900/8000 Series ....front grill discharge, you can remove that front grill to access burner/spark electrode
IF it is an Atwood 8500 Series......floor ducted registers, you can access furnace components via the outside access cover/panel
Atwood Service Manual....exploded views start on pg 39