Actually, with your trailer hitch, the weight on both the front and back axle of the truck is pretty darn close:
Front: 4500
Rear: 4580
You're only 80 pounds different. I think you've achieved (almost) perfection here.
With no trailer, there is a difference of 740 pounds between front and rear! (heavy engine, nothing in the bed of the truck -- heavy front, light in the back when empty.)
A lot of folks will haul something heavy in the back of their pick-ups just to add more weight on the rear for better traction, more weight, especially in winter on slippery roads because every truck I've ever seen, is always engine heavy, tail light.
With your trailer and set up, you have almost equal on both axles. Really! I think you've achieved it! Don't mess with it. You've arrived!