Get some trail maps and start to do some studying! If you are dead set to pack the miles on the U.P. is the place to do it and guys that can ride all day long and play up around the C-Note can pack 300 - 400 on in a day (with good conditions). 200 mile days in the U.P. are fairly easy if the groomer has shown a presence. Keep an eye on the snow fall reports page and start a new post a couple weeks before you leave so people in those area's can keep you up to date on current conditions! I agree that making a solid plan can be disappointing if each goal is not met! Unload and run as hard as you feel fit and stop as needed! Pick some hopeful spots to see and make what you can!
Maybe we can post some single direction day trips that we know are in your route and possible to do in a day.
Example: Marquette to Copper Harbor - Can be done in a day. I do believe depending on route that this is a 200 mile give or take day. Some awesome riding and varying terrain
Totally agree miles can pile up quick with some hard fast riders just running 8AM till 5PM. Still not sure of the size of your group or riding skill but 200 miles is easy in UP? If you have 20-30 riders to coordinate a whole different ballgame to coordinate with chase truck & trailer.