Paying off debts as call to Adventure: Citadel of the Scarlet Minotaur

I want to try Shadowdark and Scarlet Minotaur seems like the easiest way to do it. But I find myself struggling with a few questions.

1. Why should PCs finish the dungeon after their first encounter with the Minotaur instead of looking for easier loot elsewhere?

2. Time should always be a precious resource, but what's stopping the PCs from resting every time they lose a spell?

3. Are there any settlements nearby to rest in, or are PCs dealing with wilderness survival when not in the dungeon? Can they carouse between delves?

My idea: the PCs have debts to pay and a limited window to do it. The orphanage they grew up on together owes a large sum to the mob and only has until the end of the month to settle their tab before the mob seizes all their property

-The Citadel is the only major treasure prospect for miles and miles.

-The Citadel is far enough away that making multiple trips per day is impractical, at least without mounts.

-XP would be awarded by returning treasure to town, further adding pressure on how much they can carry out per trip.

-"The orphanage you all grew up in owes money to the mob" feels like a good motivation to get a band back together and leaves room for backup PCs to show up. (Ie the plot of Blues Brothers.)

-Since paying debts deprives players of money to carouse, the mob might force them to join a party every time a significant debt payment is made, using it as an excuse to bilk further money from the PCs or drag them into other crimes. (This allowing the regular Carouse table rewards and penalties.)

-The debt timer should be real but not force the PCs to be suicidal to pay it off. I'm arbitrarily thinking 21 days.

Is this a bad idea? Should the debt be a specific GP amount, or a more abstract "by the time you reach level 3 or the Citadel is fully explored"? Is 21 days an ok time limit?