Thats probably the best you will do with TW.... Watch what you put in the door/bunk area such as bikes and stuff.. Everything you put there will add to TW.
Not much you can do on that trailer to pack at the rear.
Get a good WD hitch. And set it up properly.
That 580lbs can become 780lb real quick.
And who are you driving with in the truck?
You probably will need coilspring help in the rear...
This is a cheap try. Sumosprings... Other wise youll need expensive problematic air bags...
http://www.sdtrucksprings.com/index.php?main_page=product_info&products_id=21954