The length of the van shouldn't matter much as the area lenthened isn't right at the rear and rear bumper area TMK.
Two biggies in the hitch biz are "Draw Tite" and "Reese" also U-Haul places frequently advertize part of their biz at some locations as "Hitch World"
Haven't purchased and installed one yet but even Wal-Mart has a selection of direct bolt on kits which state which vehicles they will bolt onto, the rating of the hitch (providing you haven't altered the frame) with brakets, and all hardware rated for a DIY installation. These seem to all fit between the frame rails leaving the outside to quarter panels free for exhaust stuff AND should allow for removal if needed for gas tank or whatever needs to be accessed in the future.
About $100 buck if I recall - name brand stuff and no doubt sold at many auto parts places also.
Those are the names and one place I know of for one stop shopping for this and total installation with wiring at the U-Haul places that do it. If they don't do the rating you want just ask who does in your area,
T
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Tom Greenleaf - MetroWest, Boston