I briefly glanced in the Suggestions board when this occurred to me several days ago, found nothing. Has anyone suggested to Toady/has he mentioned having this idea: combining Fortress Mode and Adventurer Mode? Ie: you can start as an adventurer, assemble a group of followers with various skill during your journeys, and any time you want to use those skills, be it for mining, butchering game, making crafts, etc., you "set up camp", switching the game to something like Fortress Mode. In camp, you assign tasks to all party members, such as Mining, Woodcutting, Hunting/Plant Gathering (foraging for food in the wild will definitely come in handy).
tl;dr - A toggle switch from Adventurer to Fortress and back.
Having to set up at least a temporary camp makes sense, as these tasks should take some time to complete. If you can send a few party members out to visit a nearby settlement, you could ask them to direct traders to your site next season, and so you could establish a more permanent settlement that way. There would be an option, of course, that might turn on the full features after certain requirements had been met, so that you could establish a genuine Fortress, if you wished. Perhaps by swearing allegiance to a local Entity, or declaring yourself as sovereign and defending your turf.