I needed it mounted as far forward as possible so my Harley would fit. In order to do that, there was no metal cross brace underneath in the 'right' location.
It is bolted thru the plywood with the addition of a flat piece of 1/4" steel about 12" long and 7" wide placed underneath for the bolts to go thru before putting on the lockwashers and nuts.
The metal piece helps spread the support strength of the plywood.
EDIT TO ADD: HINT: When under the unit, be sure to tighten and maybe double nut the nuts that hold the tie downs. None of mine were very tight from the factory.
2012 Fun Finder XT 276 Toy Hauler & Harley Davidson Ultra Classic with Condor wheel chock
2014 Dodge Ram 2500 AT 4X4 Crew Cab 6.4 L Hemi, 373 gears, tow package, Rambox option, Revolver X2 tonneau cover, Equal-I-zer anti-sway hitch.