Bob,

As you've realized, it takes some forethought and planning; but that's necessary with any set-up for slop free, tight control. What I do is decide the precise location of the servo in the fuse. Pull-pull elevator servos are side mounted. You either build a side mount that is screwed in from the top or adapt a plastic one.

Then I take string and use it as a guide outside the fuse, to determine the angle at which the cable will need to exit the fuse. It really doesn't make a whole lot of difference if the cables rub a little at the fuse exit but if you're going through the trouble, might as well get it exact.

The exit holes on the fuse sides need to line up with the horns such that you have a straight run from servo to horn. This isn't that tough to actually do on a composite fuse and only moderately tougher on a wooden side because of the thickness of the wood. I typically will install a teflon microtube on the fuse exits. I made a bunch of this tubing many years ago and am still working off the stock. McMaster Carr carries teflon microtubing

Finally, it helps to have Teflon coated Kevlar cabling. I made several thousand feet of this material about 10 years ago and have been using the stock ever since for my set-ups. Sold a bunch of it too. The best there is for this application. The smallest profile, slickest surface and about 80 lb test. McMaster Carr does not carry this stuff. My own stash.

The other great thing about pull-pull is the fact that you have 4 ways of adjustment for very precise movements.

Back to the SAP for a moment, I found that nitrile tubing for fuel delivery is not as robust long term. It requires changing every season. On Aesthesis I'm using polyurethane soft tubing inside the tank and viton outside. Couldn't find viton that was soft enough to use inside the tank. Polyurethane tubing was frst straightened with a heat gun and then installed. Changed the tank's metal tubing to 1/8" ID to accommodate the plastic tubing