I would buy a piece of rubber fuel hose in the right dimension, split it and atatch to protect the rack. Also a piece of alu pipe (split in two lengthwise) and glued on again would do the trick and would look better maybe. Replace when worn out.
Therer are pictures on the forum of racks peopel custom made from scratch using bolts instead of welding.
What about a small trailer- like a travoy or Andersen trolley beind the bike- or even a bigger one?
https://wicycle.com/products/bike-trailers/diy