Ifutzed around with some popsicle stick ends, 1/8" tubing, an old servo arm, epoxy and some scrap wood ...

The ply cross arm can be CA'd to fuse just behind the former and then the rest can be screwed to the ply. This will provide a straight control arm shot under the tank tray to the firewall as well as a nearly straight shot back to the SIG-provided throttle servo location over the wing tube bushing tube.

Or, I can use a HS-85BBservo mounted upside down just behind the former, over the landing gear mounting plate and call it good ...

So many options ...