I'm surprised if Selden doesn't mention anything about it if they provide installation instructions. I suspect that the forward ring takes the upward pull and the rear pad eye has a downward force and probably a shear load, as the lever is at the forward ring. That said, I'm always more comfortable with through bolts rather than lag bolts. The access underneath will either be in the v-berth or forward of the v-berth if the bulkhead is set far enough back. I read about an installation that used through bolts with large diameter washers for the backing, installed with 5200 for bedding. I wouldn't use 5200 but I would be fine with thick washers if a backing plate can't be found. But I would definitely use backing of some kind and I definitely wouldn't use lag bolts or a blind end for screws. I'm sure they recommend a minimum diameter for the bolts, or if they don't, obviously you would be limited by the size of the holes provided on pad eye.