Whiskey Tall Falls huh... Lived there back in the mid 60s to the early 70s and been going back there many weeks at a time working on the Space Surveillance system at Archer. The big then back then was trying to just have ONE BEER at each Honky Tonk from Frizzels to the DOve and survive it. I even go back to Silver Dollar days... More recently I used to park my OFF-ROAD POPUP CAMPER in the HAMPTON parking lot when it was on Maurine and now at Kemp when we was working at the Archer City site. Finally retired now - Miss my Wichita Falls trips big time... It was a homecoming on every trip... Wife is also from the North Texas area... Her mom is buried at GOBER, TX (Bonham area)- this town wasn't on the big maps until recently haha..
Your trip to Colo sure doesnt have alot of PLAN Bs in it. You will need to start beefing up your 21-footer sooner or later with smart mode converter/charger, LED lights, more batteries, and a 2kW generator. We used to stay out weeks on end tent camping with the Jeeps and utility trailers back in the 50s-60s in the high country of Arizona but even that took some planning to be successful.
We run 255AHs of Battery Capacity on our off-road POPUP and can run almost everything in the trailer except the Air Conditioner and the high Wattage Microwave and make it it thru the one day/night camping run off the batteries. Then re-charge back up with the trailer connected to the generator for a short three hour run when the batteries get down to around 12.0VDC (apprx 50% charge state). Doing it this way we can stay out for a good two weeks and still fit into most of the camp ground policies on running the generator but after two weeks we have to do a full 100% battery charge or start having harm done to the battery bank. This takes around 12 hours of generator run time which no one allows so thats when we head back for the house.
We love camping off the power grid alot. Went to Wichita Mtns Wildlife Refuge at Medicine Park many times. Was there at Camp Doris for a week just two years ago... My OFF-ROAD POPUP Camper with Virginia TAGS has blessed your area many time...
This is from our last visit at Camp Doris. Notice when we camp off the power grid and need 120VAC for a fan to blow away the mosquitoes we just plug in a couple of extension cords...

I'm assuming your name is from the HeeHAW days with the BR549 thing... That was always the phone number I wrote down when asked in my travel days
Roy Ken