During June I am going to travel from Rawlins, Wyoming to Douglas, Wyoming. For a 40-ft coach is the route from Rawlins north via 287 and 220 to Casper appropriate?
Route 220 passes by Several Oregon Trail sites. A few miles past The Devil's Gate is Independence Rock. There is a rest area at Independence Rock and a short trail to the rock itself. Immigrant names can still be seen carved into the rock.
To answer your original question, route 220 is an easy drive. We drove route 287 from Lander, so can't comment on the section from Rawlins.