the thicker the boards- the greater the stability- but conversely, the longer they will take to dry.
what is your ambient humidity there?
you can seal with some old paint, some folks use white glue, there are some commercial products like " anchor seal" . all you are trying to do is to slow down the release of moisture for the "severed arteries" in the wood- as that excessively fast drying is what will cause checking.
i think your drying plan sounds good! i wouldnt rip to the 1/2" blanks, until you are ready to run them through your jig- they will take on a life of their own, when you cut them down that small
- just keep it out of direct sunlight as that will dry faster and check.
just watch that the standing deads are sound- pine- like other soft whitewoods, can start spalting( blue stain) and decomposing- even while they are standing.
lodgepole makes great shafts- known in the industry as "chundoo"
good luck chap!