Thank you for your suggestion. I did consider doing something similar two things stopped me, the main one being I want to get the signals so they are working and the added complication of going through the platform put me off and I want to set up a test jig when I make the signals fully working and both legs being the same length will be an advantage. The second reason is my inability to cut things to size and squarely and a wonky gantry would look silly.
Clive,
This is from memory about 35 years ago when I managed to persuade my training engineer to let me spend some time on the 'outdated technology' at Exeter. If a gantry like that was on a platform, the signal wires needed to pass through the platform and turn vertically up the leg. This would be done using a crank which needed access to be oiled and greased so there would have been quite a large hole in the platform boarded over with removable planks. Turning to your model, you would leave it mounted on the baseboard with both legs the same length and the same large hole. Once you were happy with it working you could then put the planking in (to stop your little people falling in).
I too have a Tri-ang Brush 2 (and Hymeks) and have kept away from code 75 track because I imagined the flanges to be too large. Are they OK or have you re wheeled it?
Paul.