Fiberglass has it's own durability issues.

You're gonna spend a ton of time or money, probably both, getting aftermarket fiberglass body panels show quality. Especially on the huge truck panels.

If you really want composites on your truck and you have $16,000 to spend, have a competant shop fab you a select few panels out of carbon fiber. Like the hood and tailgate. Those are alright to be a little off.

The bed sides an a Styleside would be VERY hard to get straight.