No it would have to be the whole deck, the problem is bringing black smears from the painted rails into the clear deck area.
I played with a bit of CF on tail on a boad one, on the rails. I knew I had a lot to learn, but if that is what you call “pretty simple”, then I am miles further behind than I thought I was!!!
I was only referring to laying CF over the rails like deckpatch. Not to fixing your smears.
I don’t like paint in general anyway. But if I had the problem you’re describing I’d take it in the opposite direction and incorporate those smears into the cosmetics by adding to them and making them look like a choice instead of an accident. Add to them as an abstract splatter-type design and throw in some accents in red, purple and blue to give them some life.
Either that or bag a wood veneer on the deck and bottom to completely cover up the lap lines and the flats.
It won’t look like a board the pros are riding on the WCT tour but you’re already past that point and you’re not going to be able to recover it.