If you can pay off the mortgage with cash, selling F2F will pose some risk for new contacts, but will let you stack some paper useful to that purpose after you put in place a vetting procedure for prospective buyers.
For example, you could require the buyer to have a video chat with you on jitsi, so you can check him out before actually meeting in person. 

 Interesting consideration! Never thought to do a video chat. Just to have a friendly chat and set some ground rules in a friendly way 👍.

Can't zap you... please add a lightning address. 🙏