Diesel Chassis service

I might try with a local truck stop with a shop and see if they can do what you require. Most every TS in this area has an adjacent shop or a shop nearby.

Coach Specialists, who stores and does work on RVs near me, highly recommended Southwest International Trucks for work they couldn't do on my Sprinter. Southwest International has multiple locations in the DFW area with one in Arlington that might work for you.

If Denton isn't too far from you then you might try The Shop on I-35 just north of Camping World. A small family owned place that handles almost anything RV related. They're right next door to a diesel shop and I think the two businesses work together on issues as well.

Ask around and see if you can find a good mom and pop place. I've had much better luck with them than with the big named places.