It is a SENIOR strategy that requires some significant skills. This strategy works well if executed well.
Skills, in any business, can be learned, or acquired for a fee.
You need two contracts: one for the option to buy, and one for the lease. Since this client has no money it is very high risk, but if indeed dependable, you could try a low initial deposit and a high monthly option deposit that you would keep if the tenant defaults on their property purchase.
Buy Marrk Loeffler's book on this very topic !