He has arranged official papers tacked on his wall with all the information necessary for me and his family to proceed should something happen to him.

For it to be a legal Power of Attorney the agent usually needs to be named. Does the Power of Attorney he has prepared have your name specifically? Additionally many states require his signature to be performed in the presence of a Notary. You’d need to check the requirements in your state. Alternatively, you mentioned the niece. Does he have a Power of Attorney document naming her as his agent? I’m not bringing this stuff up as any kind of “scoring points”, I just want to help him and you that the preparations he’s made are sufficient to fulfill his wishes should the situation become necessary.

I’m in tight contact with his family, so really if something happens to him, they’ll come along and sort most of it out. But I know they’ll respect me, I can’t and don’t even want everything anyways. But I’m pretty sure they’ll agree the vehicle should rightfully go to me, as I do most of the work on it.

I really hope you don’t have a negative experience, but a shockingly common thing to happen is that the wishes of the dead are promptly ignored on their passing as those (usually family) are set to gain from the passing.

But I’m here to keep him living as long as possible, I don’t want a damn thing except happiness and life for myself, my mother right down the road, my roommate, and basically everyone around me…

I hear ya. We all want that, or something similar. We hope for the best, but we need to plan for the worst. This is where good and proper legal preparation during the good times can be an incredible benefit during the bad times.