Jessie, you should go over the furnace
and make sure it's working properly before you use it. If you don't know how, you may want to have a local camper shop (or vintage trailer rehabber) look at it. Most propane
camper furnaces are similar, even the older ones, with regards to how they work. Just make sure that it is in proper working condition before you use it. Its just my opinion, but I wouldn't use a propane furnace
that has not been looked at by someone with experience.
There is a group called the Tin Can Tourists who are all vintage trailer lovers and many of them restore/rehab vintage campers like yours. (Your trailer is a 'stick built' type with wood frame, etc, as opposed to this group which is focused on molded fiberglass
trailer). There are some very knowledgeable members over there, about all aspects of older campers. You may want to check out their FB group and ask this question as well. https://www.facebook.com/groups/tincantourists/