Dungeon diving and resource production. You can relatively easily pay off the entire loan (even the "impossible" 80k or whatever the final one is) by just gathering magic wood and mithril. Sell your excesses for massive profit.
The first week is a bit of a squeeze, yes, but finish like one quest and go dungeoneering and you're fine. Dungeon crawling is the fastest way to level up characters to make them better workers. Slap work boosting traits on them later and they'll gather obscene amounts of resources. After a couple weeks you'll never need to worry about money again, and the only things you need are stuff like obsidian, iron wood, adamatium, etc.