I'm going to try to make a run down that way sometime this month. But the weather needs to be in the 30's, not lots of wind and hopefully when the sun is out. Even with the sun out, some of those valley's can get pretty chilly. I just hate having my guides freeze up, doesn't make for a fun fishing trip. Winter fly fishing is bankers hours time, no need to get up at 6am IMHO. This weekend looks very promising. But that first weekend is usually the busiest, especially with warmer temps and only so many stream sections open.
Winter fly fishing is no different then just ice fishing on the lakes, same weather, but the water under a frozen ice is colder then in the spring creeks of SE Minnesota for sure. As long as you get the fish back into the water without their gills freezing they will be ok, just like when your ice fishing.
Good luck during the Winter season!