I've used these up to 400 copper. I'm sure they would work fine on a 500, especially if clipped to mono.
https://www.fishusa.com/Amish-Outfitters-Clipper-Planer-Board-Releases/
Can clean offshore, but need to keep skin on for identification. Also, you can't dispose of carcasses within 100 or 500' for shore.....I don't remember. We typically clean 'em in our last 30 min of fishing, so don't have to worry about distance.