[jtc001]

You are doing all the right stuff.

Consider a rear differential fluid change. Look for a blue tag on the differential which indicates that you have synthetic differential fluid. The stuff is expensive ($25/quart). It will probably take 2 quarts.

I monitor tire pressure a lot.

Other than just addressing your problem as you see tham - have a great trip.

As for brakes, ceramic will stop you better, but tend to create more heat. I've heard that this can wear rotors faster. Changing to ceramic will not get rid of the silverado spongy brake feel!