Any place that holds five to six feet of snow on the roof should have a steep slope to the roof itself, (or the builder should be shot). Ever taken a good look at European Alps homes and their roofs?
So, that said, obviously you are up there by Great Lakes and having issues with recent weather, and there is "hard snow" mixed in there on the roof, or the slope would slough what is on it.
I would consider first, the trek in as arduous and time consuming, (where are the snowmobiles?}. Second, I would consider it hazardous duty and want hazard pay which is premium, irrespective of the harness, etc.
So, my own perspective would be this: the trek at $30 or so an hour. The roof work, by the hour, at about $50-60. Plus meals.
And, my friend, you better get some kind of binding agreement concerning injury on the job. Obviously you don't want to do it or cannot, but even with harness, if someone takes a tumble, your liability is there.
Best bet would be to find a company that moves snow, and see if they will send someone out to do the work; you pay the company, the company pays the laborer, and the company assumes responsibility for liability/workmens compensation, etc.
Adding that there are long poles used to scrape snow off roofs available. Don't know if you are talking two story, but some of the work could be done from ground level with the right equipment, which looks amazingly like a concrete float, what they use to smooth out concrete farther out than they can reach from the edge.