I've got a few things for you, OP...First off, this is the best time of year to get over your fear!! Next time we get a cold front, you need to get your ass in the woods! The best part about winter is that the just about all of the things you reasonably should be on the lookout for do not thrive in the cold. Secondly, which part of the state are you in? I can offer advice depnding on your climate. Next, if you're worried about poison ivy, just wear pants and tall boots. This also helps with snakes, insects, and scorpions. Also, hunting stores sell cheap snake bite shields that you can put over your boots if you're in bad snake country (I'll link something similar below). Lastly, you just have to look at it as a numbers game. Not just with humans, but think about how many critters run across snakes or spiders all day every day, and live to tell the tale? This is something that helped me when I've had similar concerns....I know that if it were as big of a problem as I made it in my head, there would just be dead animals lurking at every turn lol. Think about all the deer, squirrels, and racoons that are out there every day with the things you're worrying about and live long happy lives. You'll be alright, you just gotta get out there and face those fears, and they'll fade quicker than you think. https://www.amazon.com/Snake-Guardz-Protection-Leggins-Khaki/dp/B0064RECCK/ref=sr_1_2_sspa?dchild=1&keywords=snake+bite+shields&qid=1605903078&sr=8-2-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExM0xTUTAxOTUxUjdFJmVuY3J5cHRlZElk...
This link might help. Honestly, though, if you want a really good hike you will probably need to drive to Palo Duro or Colorado Bend SP. Let me know id you have any other questions, buddy.
How many nights? Insulating a 4 person tent for one person is going to be labor intensive regardless of your method. If it's just a night or two I wouldn't bother going that far. Get a smaller pad instead that has a good R rating, put two unzipped bags on top of you while in your bag and it'll give you the desired feeling of freedom and not hiding away in your sleeping bag.
If you REALLY REALLY want to insulate it. I've bought insulator film and cut it in strips to the length of the tent to place on the floor, and took the rest and laid it against the wall.
On top of that I laid an unzipped sleeping bag on the floor then a foam pad and then my normal sleeping pad I use with a decent R rating. strung together some mylar blankets to hang from the top to reduce head space, as well as put some between the fly and the mesh of the tent. This worked really well for us when we got caught in a winter storm in Colorado with the temps below 9. The almost 2 feet of snow honestly probably helping insulate, however the wind was blowing it up under the fly and getting inside the tent. Ended up using extra myler blankets as a barrier so the warmth from us wouldn't melt it and cause us to get wet.
Ahnu Women's Sugarpine Hiking Boot https://www.amazon.com/dp/B00RWQHED6/ref=cm_sw_r_cp_api_fabc_P11PFbVWM37ZB
I use these for pretty much all hiking. I’ve had the same pair since 2016 so should probably replace them.
I don’t trail run so no recs for that.
Texas State Parks has a pretty bangin' app, on Android anyway. It lets you search state parks by feature (camping, hiking, boating, fishing, etc.).
https://play.google.com/store/apps/details?id=gov.texas.tpwd.txparks