Our rhino hose won't fit all the way in either. We have to separate it into two halves and push one section inside from each end of the bumper. It's sooo annoying. I might look at making up a storage tube for under the trailer like some folks have done. That would also solve the potential for rusting out the bumper eventually from the water getting in there.
Why can't they just make the bumper a tiny bit bigger at the factory?