Carol- Email Reggie Tours (they have a web site). They may be able to handle 22 (may need more than one "group" but for that many people they may be able to work it out. They came recommended on this board, and they seemed very friendly, informative and willing to work with us. We told them we had some people in our group of 8 that wanted to do both the tubing and the Mayan ruins tour. They could have said "sure, no problem" but instead truthfully told us that in order to do that they would have to cut the tubing trip short and we wouldn't like it. So, they get the honesty vote from me.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007