Well, I've spent a productive week in the North East staying with my very good friend Richard (he of Low Quay Yard in the competition), and we'v produced a baseboard each. They are the same design and dimension, just the track beds are different to reflect our separate plans.
We've fitted drawer runners in each end to facilitate the fiddle yards:
They are strong and secure. The idea is that the fiddle yards slot in and clamp to the baseboard, and it means that we only need two trestles. I must admit that I'm quite daunted by the prospect of designing these.
Also, I'm busy negotiating a domestic storage arrangement for the layout as it's worked on - at the moment my railway hobby is in disarray and spread all over the house - help!