Building a fence can be a good option if you want to tan naked in your backyard. Use solid wood slats for fencing and place it in a way so, there is no gap. This way anybody passing by your house will not be able to sneak a peek. Fences that are 6 feet tall can work fine unless your neighbor's yard is not higher than your yard. Building a fence can maintain your privacy as well as help you tan nude outdoors.