Using 318 mounts on a 360 .......

As long as the spacer is very tight, and everything is locked down solid, the force on the bolt and lug will remain mostly 'in shear', and this looks OK in that case. If it gets even a bit loose, then the there will a twisting force on the lug in particular that will get a lot higher than with the proper mount, and that has some increased potential to snap off the lug on a hard bump. So if you do it this way, make sure everything locks down very tight and stays locked tight.

Refer to picture: I would suggest a flat washer and lock washer on the nut side for better locking.