Pouring a concrete foundation that extends down below frost line is highly recommended. See the diagram below for details. As your propellor rpm increases, the blades act more and more like a solid sheet of plywood sitting up in the wind. Generally, anchors are designed to utilize the weight and shear strength of the surrounding soil to help hold them in place. The radius of your guy wires should be between 50 and 75 percent of the tower height.
Leveling is a an issue too.
If the guy wire pads are at different elevations, you will run into the same problems with loose and tight guy wires. The clamps should all be oriented the same way, with the forged saddle on the live end of the cable. Had we not learned this from building the bass, we would not have oriented the clamps correctly or tightened them enough. But every time we tightened the string enough to play in the key of G, the cable clamps slipped. After about 4 tightenings and the addition of more cable clamps, success was achieved.