I PMed you since your I’m neighbor hood and can answer your permit question betterI'm just north of you on Horshead Bay.
I had this guy put a helix anchor in for me in 2016:
Washington State installer of Helix Mooring anchors, Seaflex Floating Docks | Alpha Marine Installations | About UsAlpha Marine Installations LLC was founded in 2001 by owner James Jim Arnold. Our technology simplifies logistics and eliminates the need for large vessels, cranes and other equipment.www.alphamarineinstallations.com
Helix anchors have been tested up to 20,000 lb holding power.
No problems since, though Horsehead is pretty sheltered. Couple of thoughts:
1. If you have your permit, the hard part is done. I'm still working on mine.
2. Call Jim Arnold at Alpha marine and get some recommendations. The County's denial of a helix buoy may be due to environmental reasons. If you want to keep your Greenpeace card, you can follow their advice, but once you have the permit, all they look for is the sticker on the buoy--they won't dive and inspect your anchor. If Arnold says he can put a helix in, you can put a helix in.
3. I use a 6ft pennant attached to the buoy ring, then 2 mooring lines--one port, one starboard to the forward (or aft) cleats.
4. I've learned that all winter long, I have to tie up aft--to the stern cleats. In any more than about 15 knots of wind, the bow catches a wind and the boat "sails" off in either direction until it jerks against the buoy with considerable forward and sideways motion. Tied to stern, it trails straight to the wind.
4. The Alpha Marine installation has swivels at both the top and bottom, but they're not foolproof. Barnacles and the general friction of the galvanized metal causes them to frequently bind. So I often have to untwist the lines myself.
I'd be interested to hear how you got your permit. Did you do it yourself, or hire someone?