Tall Paul,
As to getting rid of the dual clevises, can I get away with just soldering one end so it can't rotate? If not, how do I get rid of a clevis...
The connection to the control surface was provided by ZB from Esprit Models. I don't know the proper terminology (combination of being a complete fixed wing novice and no instructions) but ZB supplied something that looked like an aluminium cylinder (almost like a big bicycle spoke nipple). It was too long to install as one piece in the control surface, so I cut in half and used half for the aileron, half for the flap. If you look closely at the photo, you can see one side (aileron) has a flange and the other had none. They were installed by dremeling out a hole and then I made the inside of the hole even wider than the hole in the surface. I filled the hole with JB weld and inserted the fitting. They are all very solid with no play.

Regarding some 'stuff' around the servo...that is another term I am not familier with...some sort of epoxy? Would a very thin piece of ply accompish the same thing?

Could the servos be under powered and not holding? The UBEC I got puts out 5.03 volts, but the hitec digital servos are rated up to 6 v.