There is a belly rack for the v-drive. Mine got replaced with two spare tire carriers because the under-trailer dillyo was not deep enough. The keel actually rode on the tire, and it looked like with a decent bump, you could see rim edge versus gelcoat. No esta bien, ya know?
As pimp as the under-trailer carraige is, just be aware that the bolt that holds the tire on is submerged in water every launch, and it threads into a nut that's welded to that bar there. We had to have it impact-wrenched off. We coulda lowered the tabs on the trailer, but that'd taken a welder and paint booth, or bent the rack, but it was already marginally small.
Got the side-mounts from west Marine and called it good. Still not happy with them riding so far forward, but whacha gonna do?