The angles won't affect the working of the rudder, however it will put more stress on the linkage at both sets of horns. If you use a typical clevis, it will want to work itself loose because it will try to rotate perpendicular to the direction of travel. Hold the system in your hands and over-exaggerate the angles and you will see what I mean. You could use a ball link to acommodate this rotation, but I don't trust those to stay on.

The system will work great, however, if you can mount the servo on an angle parallel to the direction of travel, as well as mounting the rudder control horns parallel. This way the linkage is only moving in 2 dimensions.

I just did this same thing in an Ultimate Bipe.