Anything less than a 10-weight is sheer folly around the oil rigs; a 12-weight makes a wiser choice. Whatever you use, make sure it has the backbone needed to pull hard on a big fish. Snapper don't run horizontally; they move up and down, and that's it. We used sinking lines between 300 and 600 grains, but because we were chumming them up, intermediate lines would have worked. Large baitfish-pattern flies like big Sar-Mul-Macs, size 2/0 and larger with heavy hooks, worked best. Jig flies also produced, but everything from Deceivers to craft-hair Clousers took fish of some kind. Chum flies proved useless, however.
If the snapper feed in schools, they tend to be less line shy, which means you can get away with a shock tippet. If they come up alone or if you chum in one location for more than 30 minutes, the fish become wary and must be taken on straight tapered leaders. I would not recommend tying your own, as even tiny knots often spooked the fish. A tapered fluorocarbon leader works bests and provides better abrasion resistance than mono. If you prefer a shock tippet, use a few inches of 50-pound mono or fluorocarbon.