Leaving the cut out in the tank(s) seems to be a constant problem, regardless of the manufacturer.
My Holiday Rambler DP I bought new in 2007 had the same problem, except it was in the black tank. Luckily, the cutout was slightly smaller that the drain pipe and, after many tries, I was finally able to get the darn thing out. I have a friend that had cut outs in both the gray and black tanks on his Tiffin DP - he made the dealer fish them out!
Out West Somewhere
2016 Sunseeker 3050DS towing 2006 Hummer H3