Mine is going to be slightly different now Nigel.
We're still going to have a 4' by 6' 3' permanent double across the back. Immediately across the front of that will be a transverse single dinette, this will convert to a single bed for the grandson or granddaughter or dog. It will also serve (when in single bed mode) as a step up to the double.
In front of that will be a 6ft galley up to behind the drivers seat, and opposite that will be a shower/loo, overlapping the sliding door by a foot or so.
It's not everybody's cup of tea, but it gives us a permanent double, a dinette, a good sized galley and a reasonable shower room.