I dont mind helping if I can. Plus I can only tell you what worked for me. It may or may not work for everyone.
If he has full access to food and water while in his cage than he will pee and poo in his cage. The whole idea of the smaller area for sleeping is that, dogs will not go where they sleep. So by keeping the cage/sleeping area only big enough for him to stand, turn and lay back down is that there is no room for him to wonder off in the cage a go potty and then return to the clean area to sleep.
So if you want to give him full run of the cage with bed on one side and food an pee pad on the other that could work. Depending on how big the cage is. I've never done it that way, so I dont know how that will work. But keep in mind once you start that habit it wont be easy to correct if you change your mind later on.
Anything at this point in order to keep your litle guy safe is worth a try !