You may find RVs in Iceland have slightly different operations than our US models. Our refrigerators use LP (propane) and 12V electric to keep cool. They don't use a lot of propane. The water heater is usually propane as well as the furnace. The two that make heat will use a lot more propane. If the furnace has a fan that will help to draw the battery down faster. The dealer should fill you in because they don't want things damaged. Travel in an RV in Iceland sounds interesting. I understand they have many woolen goods for sale there.
