Welcome, Lindsey! I, too, am a 40-year veteran of lugging gear and made the jump to GP a while ago. My former setup consisted of four keyboards and a keytar, taking up as much or more space on stage (and in the truck) as the drummer (!) but thanks to GP I’m down to one 88-key controller - as well as fewer back problems and a smaller car. 
(Well, OK, the keytar still gets in the mix for fun from time to time too!)
Others have given some awesome advice already - the thing that helped me the most was picking up a foot switch and setting it up to move between song parts. By setting up splits and layers for each part of a song and being able to move to the next one with a foot tap, I’m able to have just one MIDI controller and not need racks of synths that I can only play with the two hands I have at one time anyway. Instead of leaping from synth to synth, the sounds change under my hands for me. It takes some thought and setup but is incredibly flexible and liberating. For some great examples of this in action and to see what’s possible check out some of Francis’ videos in this thread. Dude is an inspiration, and has some awesome rackspace setups for sale too (disclaimer: I’m only a very satisfied customer!). Have fun!