Re: Engine Mods for the V10 Ford what have you done
The 10k "Tow-Rating" is limited by the factory 10k receiver. Upgrade to a class-5, and you can utilize the remainder of your GCWR. And since DOT doesn't care what your factory GCWR is anyways, only the sum of the van's and trailer's GVWRs, you can really tow whatever you want as long as you stay under axle ratings. And really, for the driving test and licensing requirements, only the GVWR of the trailer matters. (Other than the van must weigh more than 6,000 pounds in California to pull a trailer over 10k or to pull doubles).
RV-prep package is more like a trim level. It comes with some amenities to make it easier to convert, but does not come with full FMVSS compliance, so the final stage up-fitter must post their own certification.
PS - if you register the van as a bus, you can legally tow double trailers with your Class-A license in California. Just an FYI.
2000 E450 dually V10 wagon