I went the same route as PrinceofThieves and used that same post as my guide (believe it was Max366?). The original access hatch was effectively a non-starter and the first thing I did was enlarge the access so I could actually get to everything. After that it went fairly smooth though I was looking around under the deck the other day and the Jabsco pump I installed is looking pretty bad after only two years, odd as the other ones on the boat are much older and there's no sign of corrosion or wear on any of them. Probably be replacing the pump this year but now when I do it it's just a matter of removing the starboard panel that I cut to cover the new access hole and swapping out the pump.