Well...
Trailer Life Magazine had a feature article on Gooseneck adapters as sold by more than a few manufacturers and "approved" their common use. I had the same Turnover style Ball in Bed issue and went with the STAR PERFORMANCE Gooseneck Adapter that has a built in glider motion.
www.sphitch.com
This adapter was not reviewed by Trailer Life, presumably because the manufacture does not advertise in TL.
The high quality and robust lubricated SP Hitch was only a little cheaper than a good Fiver Hitch, but I also did not have to deal with removing the ball and filling the hole. The significant benefit of the turnover ball is keeping the bed easily free for other uses, which has come in handy several times.
I've towed my used 13Klbs Fiver for about 3000 miles so far (had 5000 when I bought it) and I just had the EZ Flex wetbolt/hanger/shackle upgrade installed. The old suspension parts were still in fine shape (nylon bushings intact, no elongated holes). Pinbox is still in fine shape.
I've heard of as many Fifth Wheel Hitch Frame Failures as Gooseneck related frame failures in my travels and on various RV Bulletin Boards (very few in all). Maybe if fulltiming and running over 5000 miles per year, the additional stress could become a more significant or greater issue?
If anyone is specifically inclined to purchase a Star Performance Hitch, please let me know as the company is currently running a promotion with a reward for referral purchases.
RVing still presents lots of sometimes tough decisions...