You can get rid of half or a third of the water. It'll weigh less, but since the water has more room to move around, it'll be more dynamic. Didn't Kubick compare partly-filled keg-lifting to wrestling a live tiger? Good times.
Some fun moves I like to work on:
Shouldering for time: Keg starts on the ground, keg ends up on your shoulder, drop keg, repeat for 2-5 minutes. Alternate shoulders each rep.
Rocket Launcher Crunch: Hold the keg on your shoulder, like you'd hold a bazooka (or rocket launcher, hence the catchy name) steady it with both arms, and "crunch" diagonally down, like you're doing a crossbody crunch, when the keg feels like it's going to fall, reverse the motion to stand up straight. Do 4-6 reps, then switch sides.
Zercher Lunge: Hold keg in the Zercher position, horizontally in front of you. Lunge forward with 1 foot, return to center. I usually do 3-4 reps per side, then switch, but you could try it with walking lunges if you're nuts.
Saxon Side Bend: Press keg overhead, keep arms locked, tick-tock side to side like a side bend.