It depends on what you mean by road friendly. Yes, you could ride most of the route. However, I would suggest you take the paved alternate route from Kremmling to the Steamboat as that section going up from the river is a little rough. North of Steamboat, the road is paved for the first 30ish miles. Gravel to Wyoming, some paved, then once you start the gravel again (Aspen Alley) it is gravel until about 3/4 way to Rawlins. Also, you know you can go from Silverthorne to Kremmling via paved roads.
All that said, you can also consider the great bike trail from Frisco (Silverthorne to Vail). Continue on the path to to CO-131 (west of Edwards) and then north to Steamboat. If you wanted part of the GD, once on CO-131, head east on CR-134 (near Topanos) until you connect with the GD at CR-16 which is nice (gravel, but doable).