Krylon and Rustoleum both make a Marine spray and can epoxy for boats, that is extremely crazy durable on most surfaces (I've used it on metal and plastic) and lasts just fine banging it around provided you do all the sanding and other prep work ahead of time.
The Rustoleum brand has a picture of a boat out on a lake on it and says "Marine" on it.
I've never tried the fusion stuff, maybe worth checking out.