I don't see what the point would be; Gravel is pretty insignificant and time is better spent elsewhere. Plus it'd would only satisfy existent fans of both candidates, most who already know the position of both.
Paul has a great chance; Gravel does not. Gravel only has like 10,000 to 15,000 in the bank whereas Paul has about 500K (and fundraises at an explosive rate) and a huge following.
I'd, personally, rather see the time used for something better.
He needs to debate Rudy. Should we send that Ron debates Rudy website to all the media outlets we can muster and also all the online communities that we know of? That could give us some great press.