Forgive me if I have misunderstood the situation or misread something into it.
With all the suburbs around DFW, I am amazed at a lack of cell and repeater coverage "out there." Yet you mentioned repeater congestion. Are the areas you frequently visit large ranches much further away? Ask the people there what cell carrier they use. Look up all the open repeaters in the areas. When there's no activity keyup with identification. Best to ask "anybody around?" Or call a station that just finished. Unfortunately there may not be a squelch tail, especially if the repeater has tone squelch. If success, program to memory then scan all those to determine congestion. You may have to switch repeaters depending on where you're at.
If there is fringe coverage with any cell carrier, you may want to invest in boosters for your vehicle(s) and, with permisson, the fixed locations. A major US brand is
https://www.weboost.com but there are many others. Boosters work with all carriers. In years past I've heard of one carrier that required you to get the booster from them.
It matters who you would want to talk with and how often. If only hams, operators of (congested) closed repeaters would have a limit on the number of your ham friends allowed. If you just want to talk, upgrade and get a mobile HF rig.
If you primarily want public-safety emergency contact with voice, $60K goes a long toward a satellite phone and usage. You won't be able to dial 9-1-1 so you'll need at least one number (Texas Highway Patrol). Without voice - your emergency's position could be relayed via satellite to responders via a small PLB (Personal Locator Beacon). Just one of many suppliers is
https://www.acrartex.com/products/resqlink-plb Repeaters usually talkout further than they receive. If you can hear them while mobile, perhaps for better talkback you need a higher power mobile and, if you don't already have it, a 3dbd gain antenna mounted on the vehicle's metal. Make sure the coax has not been squished, bent, or the shield is visible at any point the entire length. Unscrew the antenna from its base to check for moisture that may have wicked up. If you can hear one or more repeaters at home, a "ventenna" on a roof vent may help.
https://www.ventenna.com For destinations having open WiFi, enable WiFi calling on your cellphone. It won't work enroute, of course. Some ranches cover large areas with a combination of WiFi boosters, WiFi repeaters, and gain antennas. The equipment is solar/battery powered and mounted in outdoor enclosures inaccessible by livestock.
Adding more transmit power, if approved through coordination, to increase repeater talkout increases the possibility of added interference at a congested site and nearby. Adding a preamp to increase repeater reception at a congested site will usually cause a net reduction in sensitivity due to increased noise levels from other transmitters.
33cm range is much less than 2m or 70cm. A combiner has power loss which could increase the fringe area of all systems combined.
I agree - DON'T DO IT as you planned!
Mike WB0DZX