I am also hung thick and understand some of your frustration. I've been disappointed in a lot of jack off masturbators that are just too tight for me - they strangle my erection! The one I like the best is Perfect Fit/aka XPlay aka Rocco's "Jack Daddy". It's really best for girthy guys like us because the entrance is wide and it really doesn't narrow much along it's 4" length. Like you, I am also longer than average, so my cock extends far beyond its length. But because it's other opening is also large, it provides a good sensation going in and out of the end. Here's a review:
The Jack Daddy Is the Daddy of All Masturbators
It's currently not in stock at my favorite online sources, but the link below seems to have a better price than others:
Xplay Jack Daddy - Stroker - Clear - PF-XP15C
Hope this helps! And, if you are losing an erection, try playing with a cockring.
And, finally, you are one hellova sexy guy who I suspect won't be single much longer!
Marc