Depends on how fast you roll the trailer. I have been using a different route the last few times there and its workd great. I taek I70 to Limon, then south on 287 through Lamar and Springfield, then straight across OK, then around OK city on the south west. It brings you in just south of the track and is about 2-3 hours less time on the road when compared to the taking the freeways through Kansas and a 100 miles shorter.
The roads are 2 lane but there’s no one out there and the roads are in very good shape. There’s cheap gas in Springfield. Don’t fill in either Limon or Lamar. The only traffic out there is heavy trucks and they are rollen! Don’t get in their way.