I would start out with smart mode converter/charger mods and beefed up batteries first to gain all the knowledge of how to take care care of the beefed up batteries and how to keep them charged and ready to go. There are deep cycle battery science you need to learn...
Then adding alternate sources of energy will come next.
Windmills in the wind path that comes up from Texas thru OKLA is a pretty good wind path. It does take a steady 5mph of sustained wind to do any good with those. I'm not much of fan with the large blades you find on those but the turret type that resemble heat removal fans on roof tops really make sense to me...
Solar panels is also something you have keep playing with to get what you need. As you will learn from living off the batteries you will need something will produce a lot of DC current if you want to recharge batteries in a hurry. Each 120WATT solar panel only give you around 5-6AMPS of usable DC current so you can see from this you will need to add several of those to recharge your battery banks in short time frame.
This is why I suggest to learn all you can about batteries first. Solar Panels produce energy from the sun and it has to be stored into battery banks for you to be able to use it. It all goes hand-in-hand...
The 26-foot size trailer IMO is almost the perfect size to have. You will love that...
I was going to suggest going down to the Medicine park OKLA but I see after reading more of your post you area already aware of that nice camping spot... We have lived in Wichita Falls and learned of this areas back in the 60s. Go there every chance we we get...
I have drug my VIRGINIA TAGS to Camp Doris on many of occasions...
We are just now thinking about adding solar panels to this off-road POPUP. I can get three 120WATT Panels on the roof - two on either side of the roof mounted fantastic fan and one additional one between the air conditioner and the rear edge of the roof. Even with these three 120WATT panels only producing around 15AMPS of usable DC current during the day will not be enough to keep my 255AH battery bank capacity re-charged during the day to make it thru the next day/night running all of the things we want to run off the power grid. It will take some planning to get to where you want to be using all of these things... Right now we are able to run all of our 120VAC Toys from a 600WATT PSW Inverter and other 12VDC item direct connected to our battery bank but requires us to run our 2KW Honda Generator each morning for three hours to get re-charged back up to at least 90% charge state so we can do all of this all over again the next day/night run off the batteries. You can be frugal and make it happen with less but first you need to plan for what you really want to run and it will work with planning. My days of flashlights and candles all went away back in the 60s and 70s... Now we want to run all the 120VAC appliance we can with what we got...
We got very successful with the batteries first now we want to start adding alternate sources of power to help out and not have to run the generator as much. Seems like everywhere we go we have generator run time restrictions and can't run them when you want to. Even Camp Doris has generator run time restrictions in place. This is where using solar panels to refill the batteries during the day will help big time.
Don't think you can just jump into it and go... It will get dark on you around 10PM at night - Then what are going to do hehe... The cougars will eat you at Camp Doris hehe...
Roy Ken