No matter which approach you choose, either permanent obligations or obligations for one journey - the tricky part will be that the obligations get you a disadvantage. Either your morale is low and you get -1 on all your dice rolls, or you are tired because you had to work on the merchant all night - start fights with half stamina, or you have to wear some armor that looks good but does not give good protection. Ideally, taking no obligations will let you lose over time because you have no money for gear, healer, or whatever. Taking all obligations will also let you lose because the fights get too hard. So taking the obligations is not a double win in terms of money and sexiness, because you will not make it to the really sexy stuff. You have to find the right balance when to take the obligations.
Overall, I think the approach might work, but it will be really hard to find good disadvantages for the obligations, and even harder to balance the whole system.