I was replying, as a dedicated, woodworker/ cabinet maker. Picture 2, if glued and screwed, will happily support N gauge, and yes, may look more pleasing. Others, however, may be building a larger construction, and to that end, Picture one, is the far stronger, and the way to go. As my friend Norm Abram, would say, you only build it once, so build it right.
Picture 1 is the best. My last layout was built with L girder construction. It was an extremely strong framing and could support me (at 15 stone then!) sitting on it and it never bowed or moved! Top timber (44mmx12mm) was PVA woodworking glued and then screwed to the upright section which was 69mm x 18mm
See it here as an example.. https://www.brian-lambert.co.uk/Layout_ ... baseboards
I will go with Pic 2, looks more pleasing to my eye, as for strength it will be fine and take more weight than will ever be placed on it, the boards are only 16ins wide. Thanks all for looking. I will document the build of the baseboards in coming days.