I see other compliance's, such as limiting suspension travel for one example. As a much bigger job, but we all have sucked it up and complied.
If it comes down to comply or park it with this one? than the answer is easy. Rub it in the dirt(dummy) and tell some one who will reckon your hard done by again :'(, or get off your keyboard and grab your drill and jig saw.
A 1mm-ish piece of flat steel(stainless) plate
or- 3mm-ish aluminum plate
or- just add a roughy from 3mm-ish plastic lid of the a-hole neighbors wheelie bin to start with. Just cable tie it in place so no one can put their fingers or clothing between the chain as it feeds on to the return lower portion of the rear sprocket. Then after the first race, you can spy some clever fuks master-piece and copy it. Hell you could even bullshit how clever you are then.
I am pretty sure all bikes have Chain guides,,,,,,,,,don't they?? well there your attachment point.
We all seem to show of how clever we are on a resto when we locate and drill holes in new plastics, etc. Well this is just as simple, is just a flat plate.
If you are inclined to over engineer,,,,well then create an attachment point to accommodate a longer bolt on the lower shock mounting point(spacer if necessary).
Or in the case of a single shock,,,,if you feel like you need a different attachment point?? use metal plate and machine the same equivalent thickness of your axle spacer and use your axle to locate it. link a second point to anywhere ,,,,,so easy.
