I have a friend who has serato but no turntables so we do alot of gigs together and we take turns running around the set to switch jacks and cables so the other can spin
Get a power adapter for the SSL box. Make sure that your thru's are connected to the mixer and you can just throw on a record while you switch laptops. No need to switch jacks and cables, just unplug the USB cord from one laptop and plug it into the other