How about a Telescoping Boat Tail?
 

Hi,

Wondering what you guys think of a telescoping boat tail? Seems like it would be nice if you need to find parking from time to time. Plus I think a little cool too. Maybe an issue would be the tampering upward that goes on the bottom as it stretches. I believe you want that to be flat with the body of the car?

http://eagle-aluminum.com/wp-content...-set-02212.jpg

I think for each segment one could add a slight tamper so it is more smooth? Also, I think this would be less of an issues the thinner the material is. Thinner would be less stair way like and more smooth.

https://alcobrametals.com/userfiles/...a%20Metals.jpg

Thoughts? Would you have to move the headlights if the tail telescopes?

I prefer the idea of being able to "put away" a boat tail on the fly.

I'd hate to have to actually build such a thing, though! :p

aerohead has several examples of inflatable tails. They are promising.