The computer in the truck should record the highest overall temp that the truck has run, so they shoudl be able to tell if it has ever over heated.
If the cab has to come off again, I don't think you should be responsible for that cost. Asking the dealer to help with that seems very reasonable to me.
Unless I have you confused for someone else, I seem to remember you posting in one of the other threads that you had lost confidence in the truck and were going to off load it after the repair. If that is the case, I would at least consider trying to negotiate a trade before any further repairs.
I sincerely wish you good luck with getting this all resolved. No one wants to go through the nightmare you are experiencing.