But, while stuck even more prone I was able to play with Anyrail and ponder what could be done in that unduly popular starter size of 6ft by 4ft.
Taking one point from C J Freezer, "For my part I would have no truck with the solid 6' x 4'. " (Track Plans, 1964.) He goes on...
"But it is an entirely different matter if a hole is cut in the middle for the owner and operator. He than has everything within arm's reach."
But avoiding another feature of many of his plans, especially the earlier ones... No first radius curves (Hornby R604, R605 or equivalent.)
I didn't realise how much tougher that would make things.
Two here came out the sketching and culling process.
They can both handle three full length coaches plus a smallish tank loco as the longest train, and are designed to maximise operation.
(Shorter coaches would look better and, if compact enough, allow trains with more vehicles.)

This one has two levels, but the main oval is all level.
The through station on the oval can also act as a terminus (it needs to!).
The oval has a hidden passing loop to increase capacity, but all the points are kept in the open.
(little lift-off sections of scenery could be added if preferred.)
The shorter terminus platform is for push-pull or diesel services, as well as being the goods headshunt.
[edit: 2nd layout and comment removed: it didn't get anyone's approval, including mine, on reflection.
An extra 2ft for an 8x4 layout would feel like freedom. The hidden loops and the goods sidings would almost certainly grab at the extra length.
At this point advocates of N may well be declaring these plans as very good at showing why N should be be preferred on a board, say, 6ft by 3ft.
They are welcome to add track plans here to entice those tempted by OO in what is, for it, a very restricted space.
Chris.