I went on the assumption that I had a bent axle and replaced the 5,200lb Lippert rear axle with a 6,000lb Dexter. While I was at it, I replaced all 4 springs, U-bolts, both equalizers, all shackle straps and shackle bolts. I opted due to the cost of everything to hold off replacing the front axle until another day. As it was, not counting the cost of 2 new tires, everything I replaced cost $705 purchased retail from PacWest Trailer and Allied Trailer Supply in Sacramento.
The axle didn't look deformed in any way when I removed it. It still had the curve (pointed up). The only thing wonky that I noticed was all of the bushing were worn and egg-shaped and all the springs and equalizers had what seemed like an excess of lateral play. Whether or not it was enough to cause the odd tire wear is yet to be seen. We leave Tuesday for a planned 1,500+ mile road trip to the Alabama Hills, Death Valley and Valley of Fire. If nothing else, I've got more peace of mind.
Thanks again for all the suggestions and input from you all.