Vibrant,
I have seen this problem a lot and even had it myself and managed to fix it.
Check two things:
Take apart what ever you have to so you can inspect the fill plumbing. It should have no pinches or dips in the run. Do what ever you have to do to fix those.
There is a small line that will most likely accompany the fill pipe, and this is a major headache. This line is called the "Fill Vent" and come off the top of the fuel tank to let the air out of the tank as it is filling. If it has any dips in it, those will collect wet fuel. Then filling the tank will blow those up to the fill neck and shut off the nozzle. Do what ever you have to do to make that line not dip.
I fixed this on both my coach and a friends (different manf.) My fueling time went from 45 minutes to 10 and really full. His is better but he won't say how much.
Matt