Welcome!
I have a backpack with a molle system, it has a 2.5 or 3 liter hydration system, a mini sawyer, waterproof matches, striker and feres rod, and a lighter, lol that's about it. I'm not sure what all I should put in food wise, and I have a small side pouch that I can use to make a pretty good first aid kit
My suggestions (for GHB additions):
1. A good fixed-blade knife
2. Metal Water Bottle (allows you to boil water, for cleaning, and for use with #3.)
3. Dehydrated meals (forget MREs...they weigh more, and aren't as tasty...Mountain House makes some good ones, and can usually find them at WalMart). I generally keep a few small canned foods in as well, just in case water is scarce.
4. Ration Bars (these are similar to granola bars, but are made for daily calorie intake, Mainstay has some good ones).
5. Flesh out that First Aid Kit (bandages, self stick ACE bandages, gauze pads, antibiotic, OTC meds, sunscreen, insect repellent, HBA needs)
6. Duct Tape (can use for so many things)
7. Good flashlight
8. Decent pistol with some ammo (you are in Texas after all...sounds like you already have a Glock, but since it wasn't mentioned....)
9. Maps home (with possible supplies indicated, in a waterproof pouch)
10. Good poncho (can use as a makeshift tent even, too)
Anything else is pretty much just nice to have.
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You may want other things in your vehicle:
1. Small tool kit (for repairs)
2. At least one bottle of all needed fluids
3. Siphon kit (for gas, post STF)
4. Slim Jim/Vehicle Entry kit (check on legality in your state)
5. Pry Bar
6. Tarp and Bungees (not just for cargo, but also for a great shelter, I prefer to have this in green, as I may be able to use it to help hide the vehicle if I have to abandon it).
7. Flashlights, especially those that can magnet stick on, or headlamp style, to assist with repairs in the dark
8. More food and water
9. Empty gas can (or full if external to vehicle)
10. Collapse-able water jug
As for your home base location, the best way to survive is going to be to have sustainable food and water. You may have seen prepper shows that advocate a hoard of canned goods, etc. This is great and all, but really, we just have to look at our grandparents or great grandparents to see what to really do. Having a well, and/or rain catchment is much better than just storing water. Having chickens that give you eggs each day, rabbits that grow and breed quickly, and a good garden along with fruit trees is much better than just store bought cans, etc.