Private loan to fund primary residence renovation

[JT Longino]

A friend has two properties. The first is a former primary residence that had seen significant appreciation. The second was recently purchased to become a primary residence after substantial renovations (~$200K). The original plan was to sell the first property to cover the renovation cost, but they weren't ready to put it on the market until rates had turned and prices had dropped and they decided to rent it for a while. So now they don't have the money to fund the renovation and they're not finding lenders who will HELOC or HEL the rental property. I'm considering loaning my friend the money but am not sure how to structure it so it's legal (doesn't involve lien on the new primary residence), but doesn't leave me exposed if I'm faced with a hostile estate executor. I'm not worried about the friend.

I'll certainly plan on talking with a lawyer if we get that far, but it'd be nice to have some framing for my thoughts before I get there and some idea that talking to the lawyer isn't wasting everyone's time. Is this something that happens? Do I back away slowly since it involves a primary residence and I'm not an immediate family member? Seems like there should be a way to structure things so it's a win for both of us.