Hmmm... tie a reel off to a down line, leave it to the DIR folks to think up a way to dive solo under the ice.
The harness allows for optimal line attachment, I just use my weight harness, as that's something that will not come undone unless I absolutely want it to. I'm sure the harness is "required" because of "someone's" SOPs.
Surface tender = a darn good safety device, you're supposed to maintain contact through line pulls, something that even OSHA recognizes.
Do away with the tender & you do away with said additional safety device. Besides, it's fun to stand upside down under the ice & have the tender pull you back to the hole, almost as much fun as bicycle riding upside down under the ice.
I always had a hand loop to hang on to, in addition to a hard attachment point. Easier to maintain feel.
Two thumbs up for braided poly line, also good for wrecks because it floats.
Heck, one time the ice was so thick that we had to tunnel through the mud a ways to get into deeper water, it was "chocolate milk" time.
Maybe I'll tell the story about freediving through the ice sometime...