Gardiner is just north of New York City some 10 to 15 miles west of the Hudson River.... I think it's near New Paltz. Quite a drive for you, but it is the nearest major DZ with turbine aircraft.
There's also Skydive Rochester which is a smaller DZ close to the city, and I would not be surprised if they have had some experience with disabled tandems, being that Rochester has the highest population ratio of deaf to hearing people in the nation... but then that's totally different than dealing with para-plegics...
Check USPA's or DropZone.com's DZ list and start asking around... http://www.uspa.org is a good place to start, but it doesn't list all the DZs out there.
You might also ping Russel Metlitzky (contact via web page here). He's a T3 complete para who is BASE jumping, and would undoubtedly have some good suggestions for you. If you can come up with a good way to do a solo landing, he'd also probably be very interested in that.