In my humble opinion you've already answered your own question by describing the manner in which you "treat" your dog...
"..., I then shout him in and praise him heavily. This gets him excited..."
You have already achieved the desired behaviour in your puppy without treats, so they're simply not required.
The greatest reward you can offer your dog is your love and positive praise, which are vital in reinforcing their sense of security and their acceptance into your pack.
We were taught that using treats is a temporary measure in pet training and that once you have your dog behaving as required, the treats are to be diminished and eventually stopped.
Don't misunderstand me, there will always be a place for treats. We still use them a lot. For example, our fifteen year old cattle-kelpie-x is given dried beef liver treats when we go out. It keeps him busy for a couple of minutes while we make our departure.
Regarding his peeing inside, I can describe what worked for us...
Attempt to predict the times when your puppy might need to pee. At these times take him outside and stand with him on a grassed area, attached to a leash if necessary. When he does pee, provide the same encouraging praise. He may not pee - don't worry - persist with the predictive pee breaks and only provide encouraging praise when he behaves as required.
In the case that you see him peeing inside, only when you catch him in the act, gently but firmly hold him, place one hand on his head and push his nose into the pee. Firmly vocalise that this behaviour is not acceptable with a strong "No" or "Bad dog", but say this only once per peeing incident. Then either send or carry the dog outside and leave him alone. Don't say a word to the dog for a period of time, ignore him completely, for at least fifteen minutes.
Being ignored is very painful for humans and dogs alike. Believe me the most problematic puppy will respond to this type of "punishment" very quickly and learn the behaviour needed to ensure they are not ignored.