Let's say Reuven owes Shimon $1000 (because of a loan). Reuven then sells his only piece of land (that happens to be worth $1000) to Levi. This land in Levi's possession is now considered a נכס משעובד of Reuven's, as it was an implicit collateral at the time of the loan. If Reuven now cannot pay back his $1000, Shimon has the right to come seize Levi's new property.
Levi obviously isn't too happy about losing out on his $1000 property. What can he do about it?
I'm looking for an answer within either halacha, or whatever civil law or customs were followed in Biblical and/or Talmudic times.
Nowadays it seems that people buy insurance against this sort of thing. Perhaps they did this back then also? Or perhaps people would write in the contract that they did not have outstanding debts at the time of the sale, and if they were lying the whole thing could be nullified?