Here's some updated information I received, maybe it will be of use to someone or for my next trip.
From AOPA: Thank you for contacting the AOPA Pilot Information Center. I would suggest you contact Caribbean Sky tours for a good suggestion. They are very familiar with the area:
www.caribbeanskytours.com
(I e-mailed, but did not get a response for several days until too late) This company mainly assists US pilots flying south of the border on trip planning throughout Central America.
My hotel (Matt at La Amistad) came up with the following possibilities:
At Pavas - Ensenansza Aeronautica 2232-1248
ECDEA 2231-1025
(these two seem to specialize in turbine aircraft and helicopters, at about $1,000 an hour and up)
Three other numbers, not quite sure to whom, but at the airport, Matt thought they were promising
2231-1105
2232-1155
2231-4814