Re: anyone here go boating at blue marsh?
We used to take our 23' Wellcraft to Blue Marsh regularly. I don't think I ever saw a boat bigger than ours up there. It's a nice place to fish- and chill out. Over half the lake is no wake.
Assuming your 26 has an I/O, it should be fine. Be aware though, of your big wake (compared to the other boats) because lots of people like to ski at Blue Marsh.
Link to the lake:
http://www.nap.usace.army.mil/sb/bm_guide.htm
I'll assume you already boat at Beltsville, have you tried Wallenpaupack?