Jimster, remember, if it gets slick out, airing down, even with highway tires, helps a bunch. Kind of a pain with a dually but if she's gettin sideways on you too much, even with the camper, air down until you get some noticeable squish in the sidewalls.
Another option since your tires are almost new, is to get them siped. They will wear quicker when loaded with the camper, on dry pavement, but will do a lot better on slick/icy roads, which is the real culprit on highways. They're typically plowed well enough that deep snow traction is a non issue.
I've got some road runner tires on my Dodge right now. They snucked last winter. If I don't find some better tires, I'll sipe them before winter.