[wingnut60]

You may not feel comfortable doing this, but worked well for me--I cut the entire flange off both side plates and the trailing edge even with the hitch itself. The side plates are there to spread the holding strength of the bolts. I was told by 2 certified welders that the bolts themselves are plenty to support the weight even without the side plates. Had a 38RSSA and '17 450 with a Retrax cover. After the cuts, did not have any more hits but really had to go slow if backing sharply and off-level. Had done the same thing with an '05 36TK3 and after many miles of towing, the plate/hitch never moved, nor did the '15 RSSA.
Used sawzall to cut and angle grinder to smooth out the sharp edges.