This "not diving" is getting to me..

[DanL]

Fred,
Apologies for being "preachy", but I'm really worried about you! I don't know squat about ice diving, but I think a line tender let's out a heavy life line and then pulls it back in as the diver surfaces - a controlled and positive link to safety.
Using a makeshift harness with a loose line seems nuts to me. What if your line got snagged or anything went wrong. Free diving gives you no time margin for error on getting back to that little invisible hole that provides AIR.
Why don't you take an ice diving course and get the correct equipment and a knowledgable buddy(ies) to tend your line with the ability to pull you back to safety.
Sorry. I love the reports of your adventures, but really am getting a little concerned.
Dan