Many years ago we took our 36' DP with toad attached into the park. I did write in my log book that the road in was very steep but there was apparently no problem in negotiating it. Here is the excerpt from my log:
Tuesday 10/15/96
Left McLean, TX, at 8:45, west on I-5-->Canyon, TX. At Groom, TX, a large white cross
sits in a field, visible for miles.
59277 Arrived Palo Duro Canyon SP at 11:45. $15/day, w/e, got three days, as that’s all they would give us at a time. (stayed 5 days). Access road is very steep and winding. Big canyon, looks like the Grand Canyon, but less grand. Over the next few days we took a couple of hikes. Trails not well marked but were pretty good. Great hiking weather, breezy, warm & dry. Two weak TV channels, no cellular.
Town of Canyon pretty large, about 12-14 thousand, home to Texas A&M West. WalMart & large supermarket, turn R. on 87th N. off 127 from the park. A mile or so up the street. Supermarket right across the street from WalMart.