I wasn't being snide when I thanked Alan for the BS extract - but all it does is highlight what a mess the whole thing is. The lack of clarity on what is required and what isn't is why you get such a diversity in approach and frankly, people give up and this creates the room for dangerous or poor practice. I've resigned myself to doing everything I can that is practical, high quality and safe - but given up trying to make sense of the rest of the vague and conflicting standards etc.
Mounting a drain on the side of the tank inside the engine bay is an option - but as Tony says, the stern slopes back and realistically the drain wouldn't work to drain the real layer of sludge/water on such a large tank area.
And as for an inspection hatch - in my situation, with a 10ft wide fuel tank, I can't see it offering any real practical benefit vs the risk of leak, additional maintenance task, etc . So in short, this has been a useful debate but I've decided I won't be bothering with an inspection hatch.
And I think in my situation, if I ever want to empty the tank, I'll have greater success draining it via suction through the fuel filler, as opposed to a drain on the side. I may need to add some additional ballast to tip the boat to get fuel over to the side of the filler, but being so close to the stern it would be the lowest point.