For the time and cost it would take you to go to a dealer it would be easier to DIY. I would do exactly what you're wanting to do. Jack it up, add another bolt and vertical support.
It is a shame the way they blow these units out. Look at it this way. You have a relatively inexpensive repair to do. How about the guy with the hydraulic slide out problem that's out of warranty? I had to redo the HVAC under the bed in the basement. They had 20lbs of crud squished into a 5lb hole. Had to go to Home Depot and get some 4" duct work and redo their garbage. Every trailer I've had I had to finish what they started.
Like the saying goes. "You need to be handy or rich to own an RV"