I have a toadstoal and 2 other leathers, soon to be 3, and I have 5 pieces of SPS with no issues in my 75G. Just run some carbon in your tank and that should help. Also give them some space, I did notice LPS doesn't quite like leathers, so I keep my leathers a bit of a distance from my LPS and SPS.
I even fragged one of my leathers in the tank and nothing happened. Don't try this if you don't run carbon as the leathers release way too many toxins.