OK, I have it installed...for now anyway. I may move it a few inches...
Anyway...I decided to install the mount-bracket as close to the cab-end of the couch as possible.
Hardware, is included, of course, as well as a pre-drilled piece of plywood for backing.
The holes were originally arranged symmetrically/centered in the plywood, but I trimmed off one edge to make it mountable closer to the couch-end.
I had to cut a little notch out of the lid that covers the water tank. The table top is the one that came with the camper, now freed from its bondage to the evil pole.
Look! It's floating -- without an obnoxious pole and base on the floor!
It's not as close to the cab-end as the photo makes it seem. There'd be room for someone to sit on the short end (as long as they didn't have a big belly).
It can be swung fully over the couch to make floor room or 180° around over the floor to make couch room. (and, of course, at any point in-between those extremes)
What it can't do -- because of where I have it mounted -- is swing around so that its fully over the short end of the couch, parallel to the truck cab. It's too close to the end for the length of the swing arm.
Does this matter? Not sure yet...but it's because of this limitation that I'm considering moving it rear-ward a few inches -- enough to make the impossible position possible.
It can be positioned 180° to this impossible position -- parallel to the cab but out over the floor. Maybe I'd have it in that position for sleeping, so that I can't step on it when I slide down from the bunk.
Seems plenty sturdy.
The weak point will be the couch/storage-box wall, not the Lagun parts -- maybe I'll put in another corner bracket...