I think the slide-in-a-track idea is a good idea. It may take more space, fore-n-aft, but I think you have the space available. The pivot version will create a side pulling force that bears on the pivot point trying to pull the servo over, the structure you'd need to counter that will create friction that would affect it's smooth operation. The linear track at worst would require a slippery bearing opposite the pull in the form of Teflon or roller bearings where the servo would try to lift against the track. In either case the servo ought to mount through the rig so everything is at the level of it's mounting wings instead of sitting on it's bottom. ie: get the CE up higher on the servo.
The servo could be sprung directly to the center of the mount or a small pulley could turn a cord to a spring mounted elsewhere in the hull.
I'd suggest the track system be removable from whatever it's mounted on as a unit so you could access it from underneath instead of trying to manipulate things between rails and servos.
Tim, I'd love that offer, let me know the price tag when it's feasible - Macedonian
would look great with such a fine set of teeth.