These are very nice units that you have built Paul first class all the way. Drop down axles as far as I'm concerned is the only way to go for an ice shack, not sure why anybody would want anything else.
As far as selling them, I guess it kind of depends where you plan on marketing it. I would be quite cautious trying to get these sold in Alberta these days, possibly down the road some but not now. I could see possibly Ontario being a market but not sure if it's worth trying to market them over there.
I guess a guy could always have a couple axle systems on hand and just build them on a pre order built to suit operation.