yes it is safe to run the rims backward because the rims have a flat surface and the holes are tapered on both sides.
From what I have heard, no tall stock rims have flat centers, "Yes, the round hole rims (88.5-95) cannot run reversed. Only the "wagon wheels" (86-88)are capable of running reversed. "
Found a couple pics online,,,,

as I said, 32x11.5's on stock 15x5.5 rims, NOT flipped. Sky stage 2 SPOA, only other mods to clear the tires was the bumper ends. IIRC That IS as far as the tires turn, they should be clipping the springs in that pic. Not enough to really notice driving tho.
And a few more that are a bit more up to date,,, sorry, phone pics,

