My solution to extend my gigging life was to get a Barefaced 112 at 10kg/21lbs, a folding trolley, a D class amp at 5lbs, and as a backup, just in case I need to go even lighter, I have 2 Barefaced One10's at 7kg/15lbs. I now have 3 basses that weigh less than 3.2kg/7.1lbs and use a bar stool if my back is playing up.