When I get a new van I'm going to get the bottom fibre glassed
Been there and done it,
Its ok, but it is alot of work, and it cant see an advantage over speedliner now.
I have used protektakote, and it wasnt as hard wearing as I want.
I paid £500, for my mwb sprinter to be speed lined, and it is worth every penny, such a nice looking product, and hard wearing.