Maybe try for Russian outfits.

https://www.google.co.uk/search?rlz=1C2CHZL_enGB780GB780&ei=v4u4W7f9IYfNgAaD_6X4Aw&q=ural+sidecar+covers&oq=ural+sidecar+covers&gs_l=psy-ab.12..0i22i30k1.7409.9791.0.12967.7.7.0.0.0.0.81.459.7.7.0....0...1c.1.64.psy-ab..0.7.458...0j0i20i263k1j0i67k1.0.Qv-OJshtqEU

https://www.sovietsteeds.com/forums/viewtopic.php?t=5325

Ron

email (option): ronpier@talk21.com

Isn't that side car a little heavy for an M20 ?
I wouldn't suggest the whole Ural combination...

Hello Michael.

I have 2 BSAs with side car.
For one of them I just took the bike to a guy in Tel-Aviv and he had one made for me on the spot,
Tailored by measure, and it was not too expensive too,(That was 10 years ago, but he is still there)
And for the other one, few years later,
I have just ordered off eBay or Banggood.com a large cover (XL OR XXL,I can check) and it covers all perfectly,
And easier to cover and take off, as it has elastic band around the edge, whilst the tailored one has Velcros.

Best regards,
Noam.