That's actually what we (her and I) did for prom. But instead of trying for her best friend, he still only asks her to do stuff.
Lincpimp, we are going steady right now, as far as I can tell. I've told her this and this is why she had agreed to kind of reduce the amount of contact with him.
Sounds like a good idea, you seem to have him under control. Enjoy the "fringe benefits"!
He is probably trying to interact with the only woman who he can have contact with outside of school- your girl. Judging by the actions he has displayed so far I say it is time to move on to another friend. In the mean time it sounds like you have an awesome girl to hang out with too. If he really just wanted to be friends, he would be cool with hanging out as a group too.