We have these long-handled sandwich makers for in the campfire and grilled cheese is one of our camping go-to treats. We use a variety of combinations of cheeses and breads; it seems no pairing doesn't work. Also really good toasted over the fire (or on the griddle) is a peanut butter and jam sandwich.
My grade 8 home economics teacher taught us to spread the inside with hamburger relish. The red relish that she used is no longer available in Canada.