Considering the facts that Montana is in the middle of a record cold and snowy month and Colorado is in the middle of a record Blizzard. I'd say the chances of an early thaw in the Rocky Mountain West is decreased. But weather being what it is April could have record warm temps. So who knows?
We are planning a run up hwy 95 to Bonner's Ferry ourselves this summer. Leaving at the end of May but with other stops on the way so it will be June before we get there. I'm not sure just how crowded Idaho gets in the summer anyway. I lived up there for 10 months and didn't notice herds of tourists.