Permatex RTV Red is
NOT rated for partial or total immersion in petroleum. This is outlined on the tube and the back of the packaging.
Instead I will be using "Seal-All" which states on the packaging it is resistant to alcohol, paint thinner, most solvents and gasoline once fully cured.
My solution for a backing support is a piece of phenolic bar, sanded down to just slide underneath and clear the rivet and the tabs on the ends of the wafer were filed to allow more room for expansion.
Also while you mentioned you already altered yours as well, APD did get back to me and offered an out-of-warranty replacement if I paid shipping both ways. If people are seeing repeated failures like this they want to know and so does the manufacturer. Unfortunately I already started tweaking with mine before I got the reply and I need to be back on the road Wednesday, so we'll see how long my fix holds out and if it fails, I'll have to order another sender.