I really think you should make a dog run outside if you are not willing to crate train him. Like you said he is only alone like five hours tops. Dog run with a bungee rope and toy tied to a tree maybe? I have seen people suggest that on here alot. I reckon it's a good idea. Make sure you have all good things he can chew in his run when you're not there. I've also seen people say cut up pieces of rubber pipe is good for dogs to chew? and they last a while. Honestly think you should consider this.