There wasn't a lot we could do about it while we were trying to keep weight on Mike Wazowski without driving us all up a wall. Around the time Mike passed, we learned that PeeWee's kidney disease had progressed and he needed to start eating K/D food. Which is higher in calories. Which is exactly the opposite of what Cali needs.
So we decided to build PeeWee a feeding box. Cali's food is high enough that he doesn't go for hers, but we needed a place he could get to and she could not. We bought a cat door with a magnetic catch and installed it on the side of a large tote. So far it's working...okay.
Once he's in there, he'll eat and drink just fine. But he hasn't quite figured out how to get in by himself yet. So we're still helping him with that. He did finally figure out how to get out, though. He's getting there!
UPDATE 1/23: PeeWee has mastered the cat door! He has free access to his food whenever he likes. Makes for a much happier kitty.