You can now use any paint color you want & buy Flat Clearcoat to make it flat. You might have to spray a sealcoat over the paint you have if you use automotive paint.
I looked up 2x ultracover & see its a Rustoleum product, so you might find a flat Rustoleum product you can use.
Other wise you'll need to research compatability. Don't know if RoL has a clearcoat.
Ten yr ago a car magazine had a staffer(Randy Bolig ?) paint a car with white RoL & the finish looked good in Mag.