So many great ideas here...may I suggest another...;-)
Of course, daughter did it for free.Right after we bought property in Seagrove, we were staying on Eastern Green at Rosemary because we had a meeting with an architect. Daughter was 15. There was a wedding on Eastern Green catered by Chef Paul of the now defunct Chef Paul's restaurant in Carillon and Panos and Paul's in Atlanta. There were musicians for the wedding, but apparently they only paid for them to play prior to and during the ceremony. We were watching the celebration from our balcony. During the reception daughter asked us if she could play for them. We saw no problem with that. She stood on the balcony playing her violin totally from memory. The wedding party and guests just loved it. The bride and groom asked us to join the celebration. It was a lovely evening.Of course, daughter did it for free.

Pay close attention to the "wedding" threads!You can almost always find CD's of classic wedding music anywhere. Use a boombox and wrap it in a white table cloth or sheet behind the arch or whatever your using if any. It should be just enough and not too intrusive.
I love Handel's Water Music!Johnrudy is right.
BTW Canon is of course always classic wedding (although probably overdone). Jesu, Joy of Man's Desiring, is also great...anything Bach... the Water Music by Handel.
These are suggestions from a violinist friend of mine who solos at weddings virtually every weekend.
Beautiful!!!Now that I think about it, Water Music makes sense for a beach wedding.I love Handel's Water Music!Beautiful!!!