Don't punish him for peeing in the wrong place. But reward him like mad if he gets close to his pad. Although I can appreciate you not wanting pee everywhere, I think that by isolating him in the kitchen, you are creating a problem. Dogs are pack animals. They want to be part of the family. And peeing in the wrong place is a sign that something wrong. Try staying in the kitchen with him, or cautiously extending his area so he can be with you.
I treated a dog with exactly the same problem, but he was confined to the bathroom at night. Once he was allowed to sleep in his person's bedroom, the peeing stopped.
No self promotion please