I would get a 15 to 17 inch rim from a junk yard. Cheap, steel, plain. Then, get a stub axle and hub from Tractor Supply or the like with at least a 2000 lb load rating. No need for guides. No need for swivels. Axis of rotation for the wheel to be horizontal, running side to side. Your pull off angles to the side (for the anchor, or the glider while climbing) will never be more than a few degrees, and the rope will not want to climb out of the deepest part of the wheel. Don't add more complication than is needed. With 8000 feet of ramp, you probably don't need much more than 6000 feet of rope.

If you are anchoring the pulley (say, to a parked car), still no need for a swivel. Keep your life simple!

Just my two cents worth.

Steve Leonard