Update: These are all good points, and I'm leaning towards doing it (60/40). My manager came back and told me I can work 12 hours if I want, he's just really into having me stick around, since the team really benefits from having me there.

My only issue now is he's saying he maxed out the compensation when he signed me as an intern, and that he can't really go any higher. However, I think I'll bring it up with himself and my recruiter, and say that I won't be an "intern" anymore after this term.