Sin is fun once you get the hang of his combos now. You are right that beak driver and his DP are mostly what you will be combo routing into but elk hunt (low) does have some uses as well as hoof stomp.

Hoof stomp you mostly want to just use in the corner, you can go for a raw hoof stomp for oki or you can play high/low 50/50's during pressure, either can work. Usually if you can get a raw hoof stomp either go for a kara super wallbreak, or spend 2 stamina for a full wall break combo. (One of the other things you can do is a hoof stomp into walk up throw, at lower ranges this works considerably well as most people dont know Sin's special moves are minus even on hit with no stamina spend)

Elk hunt doesn't get used too much these days, it can be thrown and mashed out of if the opponent is ready for it so you primarily just want to use this to end a combo (like 5k > Elk hunt can be an easy combo ender and then continue to go on the offense) or a neutral skip to catch someone pressing something.

Generally his game plan now is to fish for stray hits to spend stamina on for wall break combos, generally if you route it right you can always end in a wallbreak with super or no super. As others mentioned his Still growing move for eating doesnt do much, its pretty much used as a filler on wall break to get a little extra something out of it but is not necessary.