The KLR would be a fine choice. I dont know about riding on ice though. Slick conditions can be negotiated if you take your time, but I don't recommend it. Especially with other traffic to think about.
The KLR will do 70 easily, and can handle a heavy load. It gets great mileage as well - I put a 16T front sprocket on my old KLR, and it got 60 mpg.
current:2009 KLX250s, 1975 Honda CB200t (project)