I had this idea after soldering some electronics using heat shrink tubing.
When folks weatherproof and store their boats, they use a thick white heatshrink material.
I got some of this and the tape for it from my girlfriends work..
I wrapped my stock grill, taped it up and shrunk it with a heat gun.
Since it's white and the car is silver, I sprayed 3 coats of spray on plastidip on it making it black.. The plastidip was dry to the touch within 10 minutes after 3 coats with about 5 minutes between coats (just enough so it looked solid black) works great!
It's really solid and light..
This could work for an inexpensive lightweight boat tail or anything else you can think of.
I just thought I'd share.
Take care.