I'd consider some sort of backing to reinforce the beam wall when you mount that center post. I recall earlier versions were drilled in and washers with locknuts placed in the beam to distribute the load...
I scrounged up an aluminum 6.0 casting for my F18 and it's been holding on there fine with the rear beam simply tapped for threaded screws. Mike w/ Sailmax recommends bedding his mount with 5200 and attaching it with two 1/4-20 screws also tapped into the rear beam. His boat had a lot of miles on it that way.
