I don't think you need to worry too much about UV rays. If you're using it, it will be exposed. It's made for that.
A large snow/ice load is different .... A Wisconsin foot + of snow and ice on top, slowly melting and refreezing (expanding/contracting) over a long period of time ... that could be a concern. Checking all our roof seals right before the winter sets in would be a very good step. We're not in Wisc, so we won't have to deal with the load you might have to as often as you will, but once every few years, we will have to have a plan. Don't have one yet.