I saw one in Ebay I don't know if I'm allowed to put the link but here's the product BREAKAWAY THUMB BUTTON FOR CASTING FIXED SPOOL REELS it sells for $2.39.
Yeah, but those things must add at least an extra few seconds between each cast. If your making a hundred or two casts a night/day that time adds up to a significant time not being in the strike zone. I think tape is the way to go.
I'm doing both Spence, I usually do the Plugs early morning and bait fishing usually before sunset. I might try the tape first before trying anything else.