True you don't get interview a shop when down, but you do have a choice where to take it. I lost a fan clutch east of Rapid City and was able to arrange having the part available and waiting in Sioux City. Even without the fan, I was able to tow 11K lbs across SD by watching SG II temperatures and not running A/C verses going to smaller dealership closer that had less diesel experience.
I would pay additional tow charges over having someone learn on my engine. Having a RV that is not a MH, you can even change plans and stay somewhere while repairs are done.
My engine did fine and I would still be driving my F250 if I didn't want the additional payload my 5500 offered. If you wonder why I didn't go with a F550, it had more to do value for the money and the additional 25 HP of the CTD over the PSD in the chassis cabs.