Great to see this one taken further Mr T.

As regards the scale, you can go with a number of options and get a good result. You could even emulate the Google Maps look at the equivalent resolution you're looking to produce. I suppose it depends upon the kind of feel you want from the map and the technological era it's looking to be made in. I'd say that the larger island map would put it in something of a technological age, given the apparent accuracy of the surveying.

Ah, and the gate has disappeared but a city/town has sprung up nearby! Hell of a road to get up to that place... I'll take a plane please!