I really like that idea. Especially making the symbiote more of a character. An interesting angle to take with that, instead of just making it be a voice in Eddy's head, I would have it manifest itself to him.
For example. At the start of SM3, you always see Eddy talking to a nameless guy. Tells everything to him, and this guy is always with him. Then, as the movie goes on, you realize this other guy is the symbiote projecting itself into Eddy's mind and manifesting itself as a Person Eddy sees and talks to. Basically like someone with a split personality disorder, but it's not his own mind that's creating this other personality, it's the symbiote.
And if you were in the director's chair, I would happily write a script. I hope to be a published writer one day, and if I ever got to write a Spider-man story or screenplay, I would be absolutely ecstatic.