Just do it and stop worrying about it.
EDIT: somewhat more helpfully, most trips have a max depth specified - if not, just post on the thread asking what is planned. Diving is being done at pretty much all levels from what I can see, but I guess the majority are 'recreational depth' with minimal deco etc. This being YD, you may well turn up on the boat and find it loaded with twinsets and stages - but in many cases people are using them for two dives. You can always mention it when you sign up "I'll be looking to do a no-deco dive on 32% - anyone wanna buddy up?). Just take along a second cylinder for the second dive and you'll have just as much gas
. Hardboats are generally much more comfortable to dive off, so there's nothing to worry about there.
As for a load of people you don't know - to be honest, YD'ers are all pretty much horrible people*, but if you want to dive you'll have to put up with them
*that's not true
