Promissory Note - how to secure or any ideas to help in this situation?

[Elaine Ericson]

I sold a mobile home giving Owner Financing (OF) (never again will I offer OF).  The buyer had the mobile home demolished.  Crazy I know.  She is now in arrears 3 months and has agreed to deed the land back to me and take a Promissory Note for the balance 30K.  I think this arrangement is better than nothing or me taking her to court to only get the land back.  I know she can stop paying on the Promissory Note as it attaches to nothing.  Any ideas appreciated?  She is a real estate agent but rents so no property to place a lien on.