These are made of 304 stainless steel. This metal will not rust. The flaps were tested and designed in Canada so they will hold up to Minnesota winters.
With that big a lift i would recommend the GB1223Z71-2 (https://www.sharptruck.com/truck-hardware-gatorback-mud-flaps-z71-12x23-gb1223z71-2) flaps paired with offset brackets. This will allow you get extra length from the flaps and the offset bracket will keep the tires from rubbing on the flap.
You can find the offset brackets here, https://www.sharptruck.com/truck-hardware-universal-mud-flap-brackets
This is the front and rear set. These will still install with flares. If they are the very large flares the flaps will not go to the outside edge of the flare. They will extend to the edge of the original truck fender.
If your truck is lifted or has over sized tires, there are flap options with offset brackets as well. You can find those here,
https://www.sharptruck.com/gatorback-chevy-lifted-truck-mud-flaps