A waiver will not solve the issue of negligence. What is considered negligent? Well it is not definable in any given terms. So someone sues you for having black mold in your attic and now they are permanently disabled for staying in your house for two weeks. You didn't know it was there, but you should have. someone trips and falls in your kitchen the tile is 1/96 of an inch uneven, you are negligent. Someone's kid gets scalded in your bathtub, it's your fault because that hot water heater that you just had replaced was too hot.
You can never be safe, any waiver saying "I will not sue this land owner for any reason no matter what" is worthless because even if they did sigh it, it would be deemed illegal.