I'm a PP, I, sp-CFI with land and sea ratings and I spend my summers in the Carlisle PA area. However, I sold my SeaRey last year and I don't have access to a water bird of any kind, and I assume you don't either. But, I can highly recommend Jack Brown's seaplane base in Winter Haven Florida. I got my ASES rating there 5 years ago. They have a 1 -1/2 day course which includes a few hours of ground school, as many hours of dual they can squeeze in, and the check ride. During that day and a half, we did 57 water T/O&Ls. Intense, but fun. At that time, they required at least a current PP rating. Hopefully, they have changed their requirements to include Sport Pilots. However, they don't allow any solo time.
If you are looking for a tailwheel endorsement, I can recommend Tom Harry at Bermudian Valley Airpark, Kralltown, PA. (I occasionally instruct with Tom in the summer.)
If I can help in any way, feel free to contact me.
Ray Boyles (firstname.lastname@example.org)
Ray W. Boyles