BREZY V39 CMK V374 DENNA BDR CCC is the routing for NY satellite airports to ISP (according to the TEC routes in the chart supplement). That matches my experience, too. I would start with that as a reasonable thing to file (just find a reasonable way to get to BREZY).
I wouldn't sweat it too much....file a plan, then check to see the expected routing 2 hours prior to your departure time. That should be ample time to prepare for the route. Then, of course, be prepared for vectors once you get into NY tracon. Being AF might buy you some favors, too.