You typed in the original post "I have previously replaced the 3500 lb. axles with 8000 lb. axles so the additional weight should not be a problem."
I want to get this straight. You removed two, 3500 pound each axle. Total weight capacity of 7000 pounds. You installed two, 8000 pound each axle. Total weight capacity 16,000 pounds. That is what I am reading.
Question is, did you change the springs also? What is the Gross Weight Rating on your camper? (A new 8319 ultralight is around 8,000 pounds). Did you put a hitch on the back of the trailer, and if so, what kind of hitch, what are you hauling back there?
Now, where am I going with this? If you are overloaded, you might fix what is broke now, but it will break somewhere else. Why the axle swap? Inquiring minds want to know.
2012 Ford F250 ext. Cab 4x4
2002 Jeep Wrangler Sahara
2008 Yamaha V-Star 650 Classic
2008 Work and Play 18LT