I've found the wiper seal; Norco Rv R 854056. Sold on Amazon for ~$98. it "clips into the groove and is somewhat easy to remove. Haven't put the new wiper seal back in yet, still waiting for it to arrive but hopefully not a big issue.
Norco RV 1-1/2" Slide-Out Wiper Seal (Clip-On) (This Seal is Sold per 25' slideout Seal) R854056
Doug & Wendy
2020 Ford F350 CrewCab SRW, 2018 RW 340RL, MorRyde IS, disk brakes, Goodyear G114, Demco 21K AutoSlide