If you are going to have an issue with the gray tank what better place to have it happen but at the FROG rally. I was sitting under the awning yesterday afternoon and water started pouring out the bottom of the MH at the pump compartment. It looks like it is leaking from a fitting on the top. FR diesel division is on it and I will update when they fix it.
As the tank becomes full the drain from the shower is ridged and the tank flexes causing the seal around the pipe to leak. I think the fix will be to put a flex hose on to allow both to move with out leaking.