The rear fins could be fold up counter space for when you cook. Also, if you wanted to leave the tail squarish you could purposely make a couple of fairly large rear, multi LED tail lights. Then you'd have what looks like jet nozzles.
Also, The vertical fin. Someone mentioned that it might not work well when trying to balance the hatch being open. I say that a couple of good well placed permanent magnets. One on the top of the tail and the other on the roof would act to hold it in place once opened. They sell some small button ones that are extremely strong. I've seen them in Radio Shack.
This is from a guy (me) who built a large pontoon boat using 2400 soda bottles as flotation. When I go into Home Depot I don't see plumbing supplies and deck materials, I see parts for whatever I'm building at the time. In this case I see boat construction parts. I expect you'll see Plane camper materials.
http://web.me.com/deceiver6/Deceiver/barge.html

Conform and be dull.