Is there a tonneau cover that would work on my Xtra Cab with a drop in plastic bed liner?
I'd like one of those roll back types but I'd hate to have to trash the liner to put a spray in type.

I have a Undercover tonneau and it would work great with a drop in liner, hell, most of any brand should. i have a spray-in liner thats work great, plus a bedrug, and it still fits perfect. most tonneaus these days are made to work with those kind of products.

I have a reg cab and just installed one with a drop in bedliner with over the rail liner. Used a Dremel to make the cut outs for the brackets. Just measure carefully so the bars align straight across the bedrails.
Brand I purchased SportsFlex, Lund also very popular brand. Expect to pay around 260 give or take, cheaper is not worth the trouble in the long run.