Well, not really... Your cost is $48k, you're selling at $70k so taking $5k to $10k discount would leave you with profit.
I am not a note buyer, but I have looked at selling my notes before. In general, they look for FICO 600 and above and they look for a discount on the face value of the note. Some will require some seasoning of the note, others may do double closing and pay you for your note at closing.
Lets say your note is for $40k, you hold it for 6 months, and now the note buyer willing to pay you 86% of the note value and adjust it to 10%. That means you will be selling it at larger discount than 86% as an example.
If your buyer has very good credit, you may be able to sell it at 92% although not sure what their offer is in the current market.
You should call few note buyers and see their requirements and what they are offering.