I take 2 of everything: 2 basses, 2 amps, 2 cabs and 2 sets of leads.
I have spares of everything else as well: tuners, batteries, strings, strap, earplugs and fuses. I had a Marshall in the 70's that was blowing fuses so I got in a few of every fuse I needed. I haven't changed a fuse on a gig since then, but I still carry the tub full of fuses. A few years back, I was able to save the gigs when a guitar amp and a PA desk blew fuses. I only take 1 trolley, but with the light cabs I don't always need it.
Lightweight and small gear means it easily fits in the back of the hatchback, with the rear seats up.