The SuperSport models all have double-sided swingarms. Only the Superbike models (other than the 749/999 series) had single-sided swingarms.
SS rears won't work because of the shock arrangement. The swinger is completely different.
There were different rear monster fenders that fit the different material swing arms...steel and aluminum.
yeah you'll need a monster. but possibly an 888 fender
888 was slightly different too I think. There were different iterations of the mount points on the very early Monster and 851/888