My friend was diving a short steel 80, so tank length was less an issue than tank strap location. I set the tank as low as her plate would allow for her first double hose experience. I have the same "not quite low enough" issue with my own plate and wing set up, as you saw, but I have the second, lower tank strap that I really cinch down, in case the upper band slips over the bell. The Kraken plate that's offered would eliminate this, but for now I can get by by adapting.
My friend said that she said she hated the DH reg and hoses for the first 2 minutes of our 2+ hr dive, but warmed up more and more to the reg as she dived it, and became more accustomed to it's characteristics.