I just opened the save game and I have to say:
What a great work you did here!
This is a very good map, that - as you mentioned - can be played using various types of transportation.
The only downfall - as with any small island - is the lack of opportunity to use trains (or maglevs) as the main means of transportation for passengers.
Trains are highly profitable and the best transport in Simutrans.
Again, thank you for you great job here!