I also have a P530 and trying to figure out a lot of things about the vessel.  I replaced the fridge holding plates with simple 12v Danfoss compressor, and simple evap/condenser plates. 
would like to access the lost vast volume of space under salon deck to clean out the 30+ years of collected bilge gunk and maybe put all all the batteries down there.  
also inspect the main mast step
anyideas?
lt