Shopped around yesterday and found a CV joint boot with dimensions close to what I needed to fit the cyclic stick. The small opening in the boot is 7/8" and the cyclic stick is 3/4" but a short piece of 3/4" heater hose worked well as a bushing to take up the slack.
Next was figuring out a way to secure the boot to the seat pan. What I came up with was making a wire ring to fit in the bottom bellow to prevent it from pulling up through the hole in the seat pan.
Installed the boot with the ring and hose bushing and verified that cyclic travel is not restricted and the stick still contacts the stops without hitting the boot.
Wire ring to secure boot to seat pan
Bushing made from 3/4" hose to fit cyclic tube to 7/8" boot opening