Scott-

Here is a total shot in the dark: go with gluing on the bike innertube, as you are thinking; or glue on a scrap of durable leather. You may need to go with scraps on all contact areas so that the booties feel the same when you walk or even ride. Use something like SnowSeal to weatherproof the leather.

If you don't have access to leather scrap, shoot me a note. If Arrow Moccasin is still open in Hudson, MA, I can see what they have and drop some in the mail. A nice, thick piece of elkhike might do the trick. I suspect at this time of year, we each will have difficulty finding time to cross paths.

Regards,

CamperMom