Hi Samuel, 

Yes, you could bring the compression post down to the bilge. You can confirm that with Bud. 
I did / doing a total refit of our W42.  You are correct, as the beam is there so when the boat was ordered in a different configuration, the compression post could be moved. On Cadence, I opted to keep the beam. It was very badly rusted, falling apart that I had made one out of stainless. I did that because it came down onto a bulkhead if the beam was removed. I did have to take out the bulkhead just aft where the aft part of the beam was sitting on. It was damaged & rotted from water coming down the compression post, etc. I cut the entire bulkhead out, scribed a new pattern, laminated three 3/4” Marine ply & faired & glasses it in. 

I also eventually took out all the bulkheads and stringers aft to the companionway. I redesigned the layout to accommodate new fuel and water tanks that could come through the companionway. 

Check to see if your center tanks are sitting directly on the keel in the ( what I call the upper bilge area ) . Ours were and both water and fuel corroded through contaminating each other and making a mess. For some reason, on our W42, where the upper bilge drains down to the lower bilge,there was a portion of that little bulkhead which stuck up about 2.5 “. Water draining from the upper bilge area could not drain properly and the tanks bottoms were sitting in water. 

In the refit, I made a 3” high shelf that keeps the tanks off the bilge floor so water can run through and the tanks stay dry.

I have photos of everything that I have done so if you want a particular photo, let me know.

Good luck !

Regard,

George

s/v W42 Cadence