I made a tent cake this summer for a "camping buddy" using graham crackers,royal icing to hold it together and used frosting to cover it, or you could use fondant.
lots of other ideas in gallery or Wilton book ,I think 05 or 06.
I too have a tent, and used candy melts. Just cut out a rectangle the size you want your tent to be out of plastic or parchment paper. Spread a fairly thick layer of chocolate/candy melts on top. Let slightly set, enough where it's not dripping, but not too much that you can't bend it without breaking. Bend into the shape of a tent, and let dry completely. Hope that helps.