Thoughts on converting layouts such as this to Trainz:
In this case the isle and lower penensula could be one base board wide while the upper could be two wide. Since we are not space limited I would sugest making the isle and lower penensula two BB wide and the upper three, for instance. Besides longer straight aways and broader curves this would leave more room for industries and such.
The very long hidden track section labeled "A" could easily be two shorter tunnels thanks to the extra space.
I did something like that with my version of "Gorre & Daphetid line" on the DLS.