There is a new owner for Sherco/Scorpa importer in USA my local dealer said they will order the TY125 Classic for a dealer/customer but will not stock it.
There will be a two day trial for twin shock bikes at the Mosteller Ranch at Casper, Wyoming. September 3rd and 4th put on my the Wyoming Motorcycle Trials Association, WMTA you can find more information on their website and face book page.
I have an unfinished bash plate for another bike that might work with modifications. It is 3/16 alloy 8" wide and 18" long it has a 45 bend about 4" from front end. You may be able to modify by welding wings on to make it wider. I can bring it to the vintage trials at Huffman farms.
Also try bikeboneyard.com 406 240 5749 some time they have TY's for parts or they may know of a cover from another model that might fit.
They are looking for expert trials riders to help deliver supplies into the cut off mountain towns in the Lyons, CO area the FS/BLM will only allow trials riders/bikes into the area.
Ariel Winters and her dad rode in the past and I think her dad put on some trials in ARK. and had a dealership but do not know if they are still involved in trials.