Thanks for the post. This mission is not a fair fight in anyone's book, so no hero should feel bad about turning the tables a bit.
I would add that the one time I found this mission actually easy and killed all the redcaps afterwards with hardly a scratch was not with a full team, but a duo. Specifically, I had a MA/regen scrapper who had encountered problems beating down Snap before. He was 38 at the time and had Dull Pain, Instant Healing, and MOG (1 slot in it). All his SOs were green.
Snap won the first time when I was soloing him, then I came in with everything recharged and finished fairly triumphant, but not eager to repeat the experience. Most of the times I went after him in a team of 8 with my defender, and there was mass death by people who didn't punch out the instant Snap died.
The easiest time was when the scrapper was teamed with a rad/dark defender. A Hooligan right next to Snap got Radiation Infection on him, debuffing the accuracy of the mob going for me, especially the large amount Snap himself could dish out. The various dark powers the debuffer hurled further killed their acc, and Snap got Enervating Field so my smashing damage could actually punch through, since the evil gnome is quite S/L resistant. We then proceeded to kill every redcap that came our way and the defender, at the end, asked, "Is that it? That's all he's got?"
Other sets that I see being useful are Mind controllers who can lay down many AOEs such as the AOE Sleep on one mob and AOE Hold or Confuse on another. (As always, tell the blaster not to AOE the sleeping mob.) Note that empaths are going to have a rough time healing everyone quickly enough, especially if they start running out of Heal Aura range, and defense bubbles come into their own as damage mitigation becomes extremely important. If you are a flying emp duo-ing with a tough guy, try putting a range extender in Heal Other, which has just about the same range as a redcap's bow, then hover up high.
If you insist on a big team, know that the ambushes will easily exceed a tank or brute taunt cap. I suggest bringing multiple tanks instead of just one, and split up the mobs with mini-teams of tank/damage dealer/defender-controller, with the remaining pair in a team of 8 dedicated to Snap himself.
If you can't get the coordination going for something like this, and for some reason are getting tired of doing it the way the original post suggested, there are still a couple cheap tricks for the badge/costume part hunter.
1) Friendly badge-hunting pal a few levels higher than you. Swallow your pride, don't get the XP, just score your badges and costume bits. It's better than a mountain of debt.
2) Take the mish, go out and earn a level or two before Valentine's is over, come back and fight them when the minions are gray or green. Again, not very manly, and not ideal because of the time involved, but when my level 10 BS/SR scrapper soloed Snap, I was sure he was going to die. He survived due to the low levels of the minions. During this experience, I got to count just how many there were. *Twelve* Rascals and Snap were going after him in a solo mission set to Heroic.
3) Don't bother bringing break frees or Awakens. If you're not going to slug it out with the Arachnos mobs on the fringes, nothing is going to hold you. The caps just dish out vast amounts of damage, so purples and greens are the way to go. If you fall, the Pocket D hospital is very, very close by, as are the bartenders.
Good luck, and when the evil garden gnome goes down, kick him a few more times for me.