Can you do land contracts without banks knowing and how bad are the risk?

of course -- i have covered the debt of several type contracts!!! as long as i get a good down payment i do not lose any sleep!!!

You can do a Contract for Deed... make sure you require enough down to cover legal fees if you have to forclose. This is one instance where you REALLY should pony up the $ to have a lawyer write it up for you... Mine are set up so that default is payment in MY hand by 5:00 on the day due or it's MINE again...

I don't know about they bank finding out, but the risks are VERY high. If you are the 'buyer' and you are late one ONE payment, you could find ALL your payments were RENT and you don't have the equity you thought you had. If you are the 'seller' the buyer could incur MASSIVE liabilities on YOUR properties.