Yeah, I don't have to use that particular threaded fitting--I just like the idea of putting things like this together in a way that also lets you take them apart, should the need arise. (and it almost certainly will). But that one fitting isn't the only way to do it.
I can't go straight out the side without adding another extension piece to the existing one, and possibly lowering the tank a bit--in this area, the main frame channel is completely covered by the belly pan/banana wrap; in the bumper area, not an issue...and back there, you can cut into the main 5" frame rail and not be concerned about weakening it, because the frame isn't supporting anything back there.
I showed this to a co-worker today, who is also an rv-er, and understands "dump station" issues...he thought I should go back to the bumper, because of the ease of access...old knees and backs being the way they are. It would be an awkward reach to connect the slinky if I go straight out the side; much much easier with the bumper area connection. It would be easier to plumb, too...more room to work with. I'm starting to lean in that direction.
'73 Safari 23'
'00 Dodge Ram 1500 4x4 QC