Wow, if you are 240 miles from the nearest Jeep dealer and that is in Austin, you must live in West Texas. (I grew up in Houston and went to school in College Station).
Skid plate wouldn't have caused a problem unless they had to unplug the electronics from the transmission and then plug them back up later. If they did not touch the transmission at all, then it most likely is internal to the transmission.
Is there a trusted transmission repair facility close to you?
With 145,000 miles, you should have done at least two and be looking at a third transmission service. With the engine running, check the transmission fluid level. With the dipstick out, wipe it with a white rag/towel and see what the color looks like. It should be a bright red, if it is brown that is trouble. Take a sniff of the fluid and see if it has a burned smell. If it does, that is trouble.
The only thing that is weird, is that if it was the fluid or bands, there would be warning signs, of sluggishness in shifting, not having full power. My former neighbor was a transmission repair man and once my sister was visiting from E. Texas and was commenting on her Dodge Truck transmission not acting right. She had just had it overhauled by the Dodge dealer in E. Texas and they took a long time and it didn't have the normal feel to it. My neighbor drove it and when he came back, he put the front wheels into a small depression in my back area and tried to back out. The truck would not back out. He told her to take it to a local Dodge dealer I did business with and have them open a case with Chrysler. We had to go that route because it was a dealer to dealer issue. Chrysler had my dealer have it repaired and it was charged back to the dealer in Texas.
But you did not mention a loss of performance, just suddenly going into limp mode. Of course a band could have broken, but without error codes or a physical examination, it's hard to tell, and with the dealer, 240 miles away, that's a long drive at 20 MPH.
I am fortunate in that I have a good local mechanic that not only does mechanical work, but transmission as well. I have a good friend who does a lot of his minor work himself and as a teenager worked for this fellow. Now my friend takes all of his serious work to him and just recently had him overhaul his transmission. This is why I asked if you have a local trusted mechanic, I would take it to him. (I don't trust chain shops).