Yes, its 14" from the back of the tunnel to the opening, and yes you can set up for front or rear dump, as long as the front dump exits in front of the front opening, if not you will have to cut into the F1 former and you will have about 3" of wiggle room there until you hit the landing gear mount.  With little skill you should be able to make it work either way, with little to no mods necessary.