First of all, if you don't already have reservations, I doubt you would be able to get one since your trip is only 16 days away.
I called 6 months (January of this year) in advance to make reservations for my son (7) who has cerebral palsy and his cousin. I was told my son would not be able to attend because there is no ramp to get him on and off the boat and the cast members were not allowed to lift him.
When I asked if I could go..... I was told parents were not allowed on the cruise.
I almost threw a fit and threw the ADA at them.... but I decided to pick my battles.... and this was not one worth fighting.
Besides the lack of a ramp..... I started thinking about other things.... like toileting. My son is pottytrained..... but he needs complete assistance in the bathroom. I would not expect a cast member to assist him.....that would be really inappropriate.
I also considered the fact that they would be taking his wheelchair onto a sandy area. It's hard enough pushing him over carpet! I wouldn't expect anyone to push his chair through sand. And besides that... it was my understanding they would be searching for buried treasure... if that's really the case, I didn't think my son would enjoy sitting on the sidelines watching other kids dig in the sand.
If your kiddo really really wants to do it....then I would push them to allow you on the boat..... but for safety reasons please realize they may still deny that request.