Welcome to these Forums. I have a 75 Overlander that I renovated. Since you live in the southern part of the country, I wonder if you can get buy with just 120v space heaters. Two of them may do the trick. But they won't do it in 30f degree weather. I think the original Overlander furnace was 30k btu. That is a lot of heat. Now add an electric stove, electric water heater and a electric fridge and you are going to need a lot of amps. Propane is very energy dense compared to 120v electricity. And it has a very good safety record.
WBCCI #8607 VAC Region 11
KnowledgeBase trailer renovation threads: 69 Globetrotter, 76 Sovereign, 75 Overlander, 66 Trade Wind Such fun !