Furring a moving jaw?

Hello there. I'm working on a moveable jaw resin base, and I'm wondering how to cover the gap at the back of the mouth so the mouth doesn't look so huge.

I did see this post here: http://fursuit.livejournal.com/5665744.html
but I'm looking for a few more tips. Some pictures or video tutorials would also help greatly. I'm very much a visual person, so sometimes walls of text just confuse me.

Thanks