I feel for you, OP. My DD will be 9 months at the end of May, and she wears age 18-24 month clothes, weighs around 23lb, she she's also big for her age.
He's at that stage where he's starting to go through big developments - starting to get teeth, move towards crawling, waving etc. I think that often leads to babies being more clingy. It isn't a bad thing in itself, but I understand that it can be frustrating!
FWIW, my DS never did that (he's now 3 years old), but my DD loves nothing more than sleeping in our bed. She's still bf though, so we co-sleep more because it means I don't have to be up and down to her room 10 times a night to feed her. She has a lovely habit of waking up every hour... but that's another story!
Have a search on MN for threads about sleep training, there are stacks of them which might give you support and advice. My personal view is that he's too young to grasp sleep training, and it's better to wait to a year. I know lots of people disagree with me though, so it's just whatever works best for yourself and your family.
I think you should wait till after the holiday. If you try to do it now and it doesn't work then you'll be fretting all during the hol about it. On the other hand, if you do try it now and it works, you'll likely spend all hol fretting that the change of scene will knock him off course when you get back home.
I LOVE that you think he is too young to grasp sleep training Needles. I agree and have definitely decided to wait until after the holidays are finished.
I am really hoping that when he is able to eat more and move that he will be full and tired and that will hopefully at least eradicate some of the problem. Well fingers crossed anyway! Good luck to you too.