I was thinking more of the Plastic padding Chemical Metal -
"Plastic Padding is a well-known Swedish brand sold in the Nordic Region, UK and Ireland. It conquered the world with its Chemical Metal product over 50 years ago and now delivers more than 100 products for the automotive aftermarket, industrial market and retail/DIY sector. The range consists of body fillers, adhesives, sealants and rust protection".
As I recall, back in the '70s we only had a choice of two epoxys - Araldite as a glue and Plastic Padding if a big lump was needed.
Ron, I fixed my bracket back in just the way you're suggesting - prepared it well and used a good lump of polyester and mat. I haven't used the cover much as I've tended to run the LR tank with Roadster side panels but the bracket has survived two house moves and falling off the hook on the garage wall so it seems tough. I wouldn't fancy it with a cover full of tools though. I seem to remember grinding my tool compartment out. It certainly doesn't have one now.