Well, one question.
How likely is it to be regularly hitting up town hubs?
To unload at and make inventory space
Hmmm, it depends on you guys but if you go into the shroud like I expect, things are sparse. That said, there are small pockets of civilization which I suspect you will be visiting often for supplies and rest.
I've actually kept the map vague. Partly because the land under the shroud has... changed... and partly because I have not yet made a satisfactory map for myself. I have major areas, such as a city, a castle, a swamp, but don't have a coherent sense of how I want them all connected yet.
For unloading, there should be the occasional wandering merchant sort as well. Though sparse, there is still life under the shroud. The biggest ones are a military base which is the front-line trying to fight the shades. There's a major mine under the shroud which the Black & Coustad company has been mining (turnover is a bit high, that's what you get for setting up shop in a war zone). Supposedly there is a "city of marked" somewhere. And implied in the NPCs section but haven't spoken of yet, Mr. Louis Quatorze says there's a re-purposed Colosseum the Church of Light is using as a rest-spot.
If leaving Limen via the land bridge, your first/next populated city will be a frontier town in Taphos made out of Taphos survivors from deeper in, but it's a journey. You may run by the old Marlowe estate depending on the path you go, and plenty of ruins/abandoned cities.