I'm going to be in Ko Phangan from June 18th to June 22nd, and during this time there will be a full moon party. I'm trying to book somewhere to stay, and I'm desperately looking for somewhere on Had Rin Nok as that's where the party is. I'm having problems though as all of the places say that you have to stay for a minimum of 7 nights during the full moon party period. I can't do that though as I'm going all over Thailand, Australia, NZ and Fiji, and just don't have the time to stay on Ko Phangan longer than June 22nd. Does anyone know of anywhere I could stay on Ko Phangan that doesn't have restrictions on how long you must stay there for?
Unfortunately, nearly every resort asks for a minimum 5-7 day stay if you want to book in advance.
I noticed that you're getting there on the 18th though, which is the night of the Full Moon. You always get a fair amount of people leaving straight after Full Moon, so you'll have no problem finding somewhere to stay for the 19th-22nd.
So it's just the 18th which will be a problem, but that's Full Moon anyway so one option could be to stay up all night until about 9am the next morning (I would recommend doing this anyway), and then people will be starting to check out and you should be able to find a room much easier then.
It just means leaving your bags somewhere the night before, but if a resort knows you want to stay there for a few days after the Full Moon (when it goes quiet) then they'd probably be okay with loking after your bags for one night.
Also, I noticed you wanted to stay on Haad Rin Nok (sunrise beach). That's the best place to stay, but Haad Rin sunset beach is only a 5-15 minute walk away (5 mins at the bottom, 15 at the top) from sunrise beach, which is fine for a couple of nights. so staying on sunset beach could be an option.
Another option is Leela Beach, which is a 15 walk away from Haad Rin (over a hill). It's not ideal, but for one night it wouldn't be that big a deal, and then for the 19th - 22nd you could then move to Haad Rin.
There's been a thread on FMP and where to stay just recently, maybe you want to have a look here.
Since you arrive the day of the party Emmett70's suggestion to stay up until the next morning is probably the best option.