RV antifreeze will work if you can get it into all the places it needs to be. Another option is to use a bleeder orifice valve about 5' down the well, with no check valve anywhere after that. Then when you turn off power to the pump and open up the faucets in the house, the water will drain back to the well through the bleeder. If all your water lines are sloped upwardly from the well, it will drain them out very well. If you drain the ater heater as well, then you only need the antifreeze in the toliets and anywhere else that doesn't drain.