No drain petcock... At least that I am aware of.

In later versions of this boat (Orion 27) they put the fuel tank into the bilge. Apparently the tank is supported off the bottom by some boards or PVC structure.

My tank is smaller and in the lazerette. I don't think it is any more accessible. But it is easy to get to the top of the tank, just by lifting the cockpit hatch into the lazerette.

There is nothing in the bilge of my boat... and I mean nothing. I vacuumed it out about a month ago... was bone dry and dusty. I like it that way.

As far as the surveyor issue and the sight gauge... I too have heard that, but I thought it could be overcome by having valves at the top and bottom of the sight glass... not sure though.