whoa why do you need to paint entire panels ? PLEASE post photos , I think I have an idea why you want to do this and there are other better options .
A can of paint will barely cover the top of the roof , but you would need to prep , sand , wash / dry de-wax , mask with 3m green , test spray out the cans to know how they flow and use adhesion promotor possibly also & etc etc etc x10 !!
Paintscratch uses their own blend of paint and only their clearcoat is compatible technically . Using other clear will peel within a few months if it last that long even .
Please let me know why you want to paint entire panels ?