If I were coming to Colorado from north Texas, I would get off I-40 onto US 287 in Amarillo. It's a good road, no steep grades and no problems for RVs of any size. Most of the Texas segment is even four-lane. I know it well because I have been driving it for 57 years. Take US 287 to Lamar and then US 50 to the Lake Hasty campground at John Martin Lake State Park. You will have electricity, easily accessible water hydrants, a easy-in, two-lane, paved RV dump, flush toilets and showers, laundry, shade from huge trees, and pull-thru and back-in campsites, including some backing up to the small lake. Then just continue on to Pueblo on US 50 and Colorado Springs on I-25. You might even want to stop at Bent's Fort National Historic Site when you go through La Junta.
