what heter? you are not allowed to do non-interest loans to non-Jews. Are these loans predatory? if you are serving small sums to very unreliable clientele, and there is sufficient competition, you will probably be lucky to make even. But consider that you might need to start dealing with shady people in order to enforce proper payments. Not sure why one needs to go into such business in our times v. the times when non-Jews restricted our activities to such industries. Father is supposed to teach a son a business that is clean and not very hard.