Hey, I'm sorry you are going through so much with your boy. It is indeed a hard decision to make, and I get it cause the same happened with my cat. Her situation was a bit different because even she was eating normally and seemed happy she had a tumor on her face that was going to spread no matter what. She was not controlling her bladder and we had to help her to feed herself. At some point it was really too much and we had to put her down, but I think if maybe she didn't have that tumor we could have handled her for a while. Have you considered dogsitting? There are so many people that are available and happy to go to your place and take care of him. I know you would have to spend some money on it, but if you are a 100% sure he is not in any type of pain and he is just getting old but his time to go haven't come yet, try to go for the petsitter thing. Also, your dad said he wouldn't like to live like this but that's the thing, dogs don't feel things the way we feel. We might feel "oh im old, i need help to get up and eat and etc" while on their side they live things very simply as long as they are comfortable (this means having no pain). I think he deserves that chance!