Coolwhip, you and I play that MU WAY differently, so keep that in mind when I give advice, because I'm basically going to tell you what works for me, and it may not work for you.
First off, while I too love FLUDD in this MU, I find it best uncharged to send grenades back at him, or as a gimping tool. I'll also try to use it when he's near the ledge to get him offstage, to be able to punish his ledge options and/or a landing. Oh, and FLUDDing Snake into his mines, while rare, is fun.
Fireballs are awesome here. However, I have not had much success camping as you were, and usually prefer to mid-range camp, as well as use a LOT more Bair. With the two together, you can bait tilts and punish. Maybe I just do that because that's how Kirby does the MU too though? *shrug*
B reverse fireballs are very helpful in general, but also very much vs Snake when you do the above strategy. They'll expect empty SHs and spaced Bairs, then you B-reverse Fireball>Dsmash.
Dthrow is great, since 90% of the time, the Snake will AD, and you can just wait and punish, even doing another Dthrow and resetting. If you're afraid they might jump, Dair is a great option. The only thing that could be a problem is if they Bair, but very few Snakes do, especially not the first few times.
In close range, jab is godlike. It beats his options IF you're in range, and jab canceling is great, since pretty much all follow ups put him in the air.
Yeah, that's about all I really know for that MU, and IDK how much of it you can use, since you seem to play it very well, but VERY differently than I do.