Hi, BJFarar
Welcome to the forum
Not sure how big your "Camper" is. or what type heating you have.
A propane furnace will not increase the humidity, by raising the air temp. you lower the humidity of the air and reduce the condensation.
The furnace uses air from the outside, and exhaust to the outside too.
But if you use the stove, baking/cooking this will increase the humidity, also taking a hot shower, drying cloths too.
You should NEVER use the stove to heat your camper
In order to stop the condensation on the windows & walls is to lower the moisture inside the camper.
A dehumidifier will do this.. or open vents to let the wet air out.
Another thing you could try is to warm up the camper before using it.
Water forms when wet air makes contact with a cold surface, by turning on the heater (propane or electric) and warming up the inside.
This may help reduce the condensation.
Hope this help.. good luck
Take care
Bob