^^^Thats a pretty good idea.
I work in paint & body, and we have to use an adhesion promoter on plastic parts when spraying primer/sealer/basecoat/clearcoat. You can buy a non-commercial version in a spray can at automotive parts stores and is commonly called "bonding clear". I dont have much experience with plasti-kote spray paint, but if it doesn't work out you can easily remove it with laquer thinner. Use gloves if you have to use it, it burns like crazy on more sensitive areas of skin.
As far as handling abuse goes, automotive basecoat with a catalyzed clearcoat just about the most durable type of paint available VS anything laquer based (spray paint) without a catalyst. Only problem is not everyone has a HVLP or equivalent spray gun to apply it, and the cost of buying one would not justify its use.
I know I'm starting to ramble on here, but I guess the bottom line is that there isn't really any good option for trying to paint FRN that will last-just my $.02. If you find something that works let us know.