Not sure if this will work

I have a potential deal. Let’s see if this will work.

Buy subject to 635K no money down. Seller wants to carry 60K straight note due at the end of the option period. The seller will also give me 20K upfront. Investor put in 100K worth of work and the market is saturated. It has been on the market nearly six-months and can’t get rid of even after 4 major price reductions. The market analysis (BPO) came in at 775K. PITI is 3600/month

Lease option/purchase at 775K for 2399 month (market rate) plus down payment installment of 1300 per month for 5 years. I am planning to take 10K option consideration.

Now I will make my money upfront, but how do I protect myself against a market downturn. What if the property does not appraise at 775K 5 years from now?

Have equity in the deal first. Then push comes to shove, do not execise your option, let it expires.