I'm 69, been playing bass since 1968. I've gone to light passive 4s, roasted bodies and necks, light strings (Sunbeams), 1.6" nuts, 7.25 radius shallow "C" profile, heavily rolled fretboards (flat fretboards and deep D profiles have caused me issues/pain). My career has been extended. I don't want to give up superior (to me) 34" scale tone. My 2 main players are 8 lbs 5 ozs and 8 lbs 8 ozs. Sadly, my 5ers (Dingwall SJ5XXX, Lull T5, and Roscoe SKB 3005) all at 9.1 lbs are beautiful decorations. My 4s have drop D tuners, so unless I play in another Country Band, no more need for 5s.
BTW, it also helps to keep your own body weight down, do some cardio and light lifting, and glucosamine can be your friend. Oh, and Lakota buffalo hide straps are light, have some slight give, and are beautimous.