1) Would you agree with me that the two axles are out of alignment with each other?
Sure they may be out of alignment with each other which happens more than some may think. However just because tire gap is different doesn't mean the axles are out of proper alignment for best tire wear and straight line tracking the tow vehicle.
My present '97 5th wheel trailers tire gap has been 5/8" difference since the trailer was new. This trailer has close to 150k miles on it. I usually run the LT tires around 50k-55k miles before time to change .......the tires wear pattern has always been very good.
If the trailer straight tracks the tow vehicle and no odd tire wear issues I wouldn't mess with it.
A big rig trailer repair shop can check to your satisfaction.