Okay, I'll take a shot. N US 191 to I-80. W to US 30. N to Montpelier, ID. Now you have a choice - you can stay on US 30 N and then take I-15 N to Idaho Falls, then US 20 to Ashton. This route is relatively flat and a pretty easy pull.
If you want to see the Wyoming Range and the Tetons, take US 89 N from Montpelier to Alpine, WY, then US 26 to Swan Valley, ID, then ID 31 to Victor. It's a decent climb between Swan Valley and Victor, but doable. Then take ID 33 to just past Tetonia and turn right onto the last stretch, ID 32 to Ashton.
You may be tempted to take US 191 and WY 2 over Teton Pass to get to Victor, but it is a 10% grade on both sides of the pass and probably not the best choice for your MH towing a F-150.
2007 Jayco JayFlight 27.5 RKS
2014 RAM 3500 SRW CC CTD 68RFE
