We have a similar truck and are looking to upgrade the fiver. Our maximum gvwr limit is 10,000 lbs which means a 27-28' with no slide, a bit shorter if slide equipped. As was mentioned, 20% hitch weight puts us right on the limit for a 2500. We also do not want to upgrade our licenses to allow for a heavier trailer.
As far as slider hitches go, you may or may not need one. If the front corners of the trailer are cut away for additional clearance a fixed hitch will be fine. Our old trailer does not have this feature and yes we have experienced the very expensive consequences.