I bought the Forespar dinghy spinnaker pole kit, which comes with 6' of 1" OD tubing - this allows one to cut to size. I'm going to a cross check the proposed pole length to the j measurement (forestay to mast) prior to the application of blade to metal. Cut twice measure once?
I've kayaked the upper portion of Priest, but not sailed it. I'm a homebody except for an occasional dinner visit to Elkins. If I were going to sail, I'd put in there as I think the upper portion of Priest is stunningly beautiful. But I don't know the wind patterns there. On Lake Pend Oreille, we tend to get a nice afternoon breeze through the Clark Fork. But, Priest Lake is definitely worth a visit.