"Even at lvl 74/75 I don't suppose I can solo it"

Nope. You won't be able to. One of the parts to the chain requires you to have at least four people in the group to summon a boss.

Fortunately I thought ahead and got these quests done in the lull between the end of Hallows End and the release of Wrath. :)

My realm, Darkmoon Faire EU is really light on the horde side and I've struggled to get groups to help out. I suppose the achievement might mean there are a few people who want to go back and do it. Christmas cheer and all that! :)

Not all of the winter's veil achievments have to be completed during winter's veil. if you can stock up on the preserved mistletoe and eventually get it done, you can do that part during the summer

Ahhh... that's good thinking Meta. Thanks for that, I will give it a try after all!

There's still hope:

I bugged a holy paladin into helping my death knight get the Ogrila dailies attunement. Each time I'd fly out to one of the bosses to kill, either horde were there killing it already or it was dead. Each boss drops "ground loot" meaning everybody around can loot it.

Next, the five-people-to-summon boss. Great news: They don't have to be in the same group OR even the same faction. I was one, my paladin buddy another, some other alliance we weren't grouped with, and the other two were horde. Boss showed up, we all killed him in about 6 seconds, ground drop loot again.

For the final boss in the chain, it's once again ground loot. Horde were there killing the ogre spirits to summon the boss, which I tanked/killed along with them. Ground loot.

Caveat: That's not all you gotta do: You must then do the quest to get 5 apexis shards, then the first "simon-says" quest. Then you must do "Our boy wants to be a sky ranger" or whatever it's called which involves you getting a total of 20 more apexis shards and a little travel. At that point you go and talk to one of the people at the flying area and he has you talk to the NPC for the bombing quest. You do the bombing quest once to turn it from a normal quest to a daily.

At long last, you're ready to do "Bomb them again". I did it with the reindeer mode activated the entire time, but I've read that as long as you are in reindeer mode when you turn the quest in, it completes.