[TexasCamper]

Sorry to hear of your challenges.
Some other thoughts...
(a) when you get going again, may want to check tire temperature and pressure every 100 miles, comparing the right from left sides...maybe you can detect something happening?
(b) Although blowouts of 14" tires is a well documented issue, let's not rule out other culprits: is the right wheel misaligned causing the tire to wear unevenly? Could a foreign object be rubbing against the tire that causes its demise? Could a damaged rim cause these blowouts?
(c) Could the trailer be unbalanced causing excessive weight on the right side vs. left?
(d) You mentioned that you serviced the wheel bearings before the trip. In my line of business, sometimes maintenance on a piece of equipment causes something else to break.....so could something be off there? Have you or an auto mechanic double-checked the bearings?

-John