Bear - Training an Outside Dog to be an Inside Dog

Bear is a 6 month old lab mix puppy that has mostly been outside and kenneled, not being left to roam around in the house very much at all because he would walk around his house and pee everywhere he would walk.
I'm babysitting him for a while, probably for a month or so and my plan is to have him completely housebroken before he goes back home. He was brought to me with his kennel and that is where I keep him at night or if I'm not home with him. My two dogs are housebroken and usually I let them have access to water when ever they want it but this week with Bear here, the rules have changed. No water sitting out in bowls and I make sure everyone closes the lid on the toilet. I have been taking him out every two hours. At First I would take him outside, he would do his business, pee and poop and then I would bring him in the house. It seemed like as soon as I would bring him in, he would pee on the floor. I got an old towel and would wipe up his pee with it and put him and the old towel in his kennel, he has never peed inside his kennel since he has been here. Every time he has an accident, I do the same thing each time. I take him out now, every two hours, leave him on the run for ten minutes, bring him in the house, have him wipe his feet and pet him. He is doing really good!
Hopefully in the next week or so I will be able to only put him in the kennel at night. Surprisingly, he really hasn't been chewing up anything. I gave him a chew toy but he really shows no interest in it. The sad thing is, every time I train a dog for someone else, I'm sad to see them go because I tend to get attached but know Mommy, Daddy, the rest of the family and puppy will all be happier and he will have a forever home! People are less likely to re-home a puppy or dog that is housebroken and follows commands instead of doing whatever they want to do or are left unattended outside. Outside dogs tend to be neglected or forgotten.