The 1st wall is placed:
View attachment 254311
With the 2 cut 'ears'.
A small plinth still has to go along the wall
to get the connection tight at the bottom.
And I can separate the 2 halves leaving everything in place:
View attachment 254312
I didn't think a straight cut wall would suit all shapes of the BN. Therefore let the two wall parts, each with their own pattern, nibble away to nothing. With a large piece of frame still visible.
The top side of the wall is therefore equal to the bottom side of the deck beam.
A 1st view with the 2 halves on the 50mm supports:
View attachment 254313
You can see the 2 'ears' hanging in the top part below the deck beam.
With the view from the front:
View attachment 254315
When all interior work is in place, all tops should show the shape of the main deck.
Still, it's nice that what came up in my mind has worked again.
Gr. Peter