better truck brakes?

rwiegand wrote:
It's going to the shop for a thorough going over on Monday, so we'll see what they say about the rest of the braking system. This will be my third brake job in 40K miles, but one was a frozen caliper that cooked the right front, so I suppose that doesn't really count. The truck is only used when it's fully loaded, so very low miles and a lot of sitting. Since the last incident I've been trying to drive it once a week rather than letting it sit for months over the winter to keep things from seizing up. I seldom go over about 58 mph and try really hard not to over-use the brakes. Am I wrong in my understanding that the "tow/haul" mode invokes an exhaust brake?

No, tow haul just changes the trans shift points, and importantly lets it hang in a lower gear longer both up and downhill. Diesels have poor compression braking. An exhaust brake restores this and then some.
Back to your brakes. If you had a frozen front caliper then it's likely your rear brakes could be froze up. My 07 has been driven almost daily since new and in less salt than MA and it rusted out the rear pad backer shims and was about to mess up the calipers.
You're on the right track, get all the brakes checked out, including the trailer. I would expect to be wrecking front rotors if the other 3 axles aren't doing their job 100% when you hit the brakes with a load like that.
You're also on the right track. Lack of use and moisture/corrosion is the enemy of vehicles and it's greatly exaggerated in older vehicles. And brake systems are one part you can't really help along with lubricants or corrosion inhibitors like other systems.