One point of the original post was trying to set up a dual elevator servo on a particular airplane. I have two aircraft that have the split elevator setup, but used one servo to control it. It just requires careful setup using two side-by-side pushrods. See the picture. This way, you can set up your elevator on the elevator channel and just forget about it.

Proper and careful setup of the length of the two rods, one on either side, then the adjustable clevis on both ends, well, you've got an easy and strong system. I use this on two large aircraft and both are fully aerobatic with no tendency to soften in strong loops. Smaller aircraft can use the 2-56 carbon rods and the larger ones can use the 4-40 carbon rods. Either way, you save weight by removing one servo and put the servo around the CG for control rather than two back where they can cause CG problems.

DS.