The dims on mine, which I didn't fit, are
the frame is 1170 oa wide,
On the LHS it's set 50mm away from the D post, to allow the top corner of the seat to clear the tumblehome of the wall.
On the RHS its 15mm away from unit, which looks a good gap. My unit is 450mm wide. This is with the ubiquitous carpet lining.
BUT if you are buiding a side unit, consider
(imho) the seat belt "buckle" is not a very good design on these beds, as the buckle is mounted on a piece of loose webbing, which disappears into the void under the seat when you pull the bed out, and is a pain to retrieve.
I suppose it's Ok if you never go camping with passengers, but to my mind it's pretty poor. (someone please tell me if I've got this wrong).
What I've done is to route the webbing round the outside of the bed frame, and fasten the buckles to the wall with lightweight bungy cord (which I assume will be irrelevent in an accident). On the RHS there's not enough room from the unit for the seat back frame to pass over the buckle. I ended up cutting a recess in the side of the wardrobe to accomodate the buckle, again holding it in with bungee. This now works well- the belts are always ready for use.T:
When I fitted my cabinet then ordered the bed 3/4 Cannonforge was very help full. He can make any size as long you give him the information he ask for like i did and he fitted it for free. hope that helps T: