Right now I've a good steel tall Panasonic road frame I've made into a low gear single speed (fast start, easy dirt trail, great on the street) bike. Straight, low, and narrow Richey handle bars. I love it, the simplicity, frame geometry and lightweight. Sort of an urban 'café racer'. It's just great to ditch the derailleurs and cables.
Trouble is, it's road tires and not good for mud and grass.
I'd also like disc brakes and 26" wide tires (won't fit my wheels).
No shocks wanted, I'm old school. Shocks just add weight.
So...who makes such a thing (inexpensively)?

The wide tires won't fit your wheels? Or they won't fit your frame? Or both? If they interfere with the frame, it might be possible to "adjust" the frame, aka very carefully bend it for clearance. It's generally agreed you can do this once to a steel frame, but I make no gaurantees whatsoever. Do so at your own risk. You should also measure your fork for clearance with the front tire. As far as inexpensive wheels go, I know the Sun Rhyno Lite wheels are a popular inexpensive option. Definitely not the lightest, but durable and a good value. Never owned any (my department store bike is enough for me). So again, I make no gaurantees. Good luck.

P.S. I am also in East Texas.

Inexpensive is always an issue when it comes to good bmx bikes. I would recommend checking it out a community with a more of a diy type of approach, such as: https://www.bmx-forum.com/forums/bmx-bike-tech.20/
I think there will be one or another cheap possibility to realize your idea without going broke