Stratman, when you say erratic flight does it mean erratic behavior on every axis or just one? If your crystal was loose you probably were getting intermittent control as soon as the engine vibrations acted on the receiver. This is a more logical explanation than an increase in tail area. I have played with tail area many times and all I found was more sensitivity to operator input but no instability as long as the center of lift is recalculated. I remember a friend found an ugly stick in the trash and we rebuilt it with a ridiculous extra large circular vertical stab with a happy face. It flew normal with no bad tendencies until one use the rudder, where it will start a spin in a split second. But as soon as you let go of the rudder it center itself and continue flying. Thats why it was so strange that it would work against a stabilizing condition.
As far as the receiver mounted on the side of the fuse that would be "ok?" on gliders since there is no vibration but still I wouldnt recommended. In the even of a crash you want some cushion for your electronics. Now, as far as power flight.....ALWAYS isolate your receiver from the rest of the airframe as much as you can....thats why the common practice of wrapping it on foam cushion. Sorry about your crash bro.