I understand the desire for tapered roller bearings, nothing wrong with going that rout if you can and want to.
However I expect the original ball type will handle what you're asking of them just fine and save a lot of trouble, expense, and aggravation.
First weight, the camper should be predominantly over the rear axle so not a lot of extra weight on the front. The GVW of 8,800 lb leaves about 4,400lb of capacity after subtracting the truck weight which is double your camper weight estimate, not even close to overloaded.
Second speed, the 1/2 tons have similar bearings and travel at higher speeds, and 10-15 mph over stock doesn't seem that extreme. My modern car has ball type bearings front and rear with not a much distance between the inner and outer bearing halves, and it rolls along at a pretty good clip on smaller tires, so even more RPM.
Third side loads, I don't think you're imposing any more than the original truck. When I was younger I drove mine quite fast into and through the corners which would give pretty good side load and had no issues. You're unlikely to take the corners unreasonably fast with a tall camper in the bed. And straight line driving as you might do when traveling shouldn't produce significant side loading on the bearings.
Again, if you want to research and troubleshoot and make up some drawings of what needs to be made to use tapered roller bearings please do. That info if easily achievable would be beneficial to others, but as of yet it hasn't been done, there might not be an easy solution.
In the meantime I'd use good quality and suitable grease, torque and adjust them per the book, and check the temperature occasionally just for piece of mind. The cost of some spare original type bearings and seals in the glove box might be more agreeable than the head scratching and frustration of trying to adapt other bearings. But if you do be sure to let us know the details!
Grigg
