What a helpful and useful post! Thank you so much!
A couple of minor edits:
-- I think Andy said when he was designing the Big Mitt that it was going to be in the Kephart family.
-- My Bushcraft Karda handle is 4.75", which I think is about average.
-- The Camp Muk I owned had a handle that was 5.334" long. I don't know if that's because it's way out of normal range or whether handles of other Camp Muks are also sometimes that long.
-- The Woodsman I own has a handle that's 5.314" long. As with Camp Muk, I don't know if that's within range or not. I do know that another Woodsman out there has a handle 5.250" long.