snappa on all my CMP planes I have used a few control options that may help your concern and they have never failed me .
option one
1)4-40 rod -heavey duty connector
2)take a small dowl-channel out a small line for the rod to incert or "lay flat "aprox 2" long .
3), wrap with sting , expoxy and incert into carbon fiber light weight long push rod
4)Do the same thing at the opposite end .
5)WHen exiting the plane you use typical red pushrod tube that allows the 4-40 to escape the fuse in a smooth manner
6)Yuo make sure you have clearance inside the fuse so that the carbon part of the rod is not hitting the fuse
7)This provides a light weight non flexing very strong rod to the control surfaces and the internal servos .
8)WHen approaching the servos or any internal support again its a simple matter of usieng red push rod tube that allows support to the 4-4o rod and allows movemnet .
Also in my seafury I made the Y set up you discussed with two 4-40 rods , and the rest of the set up was the same .
I can achieve no bind movement and no flex at all under load with this method .
Your concerns as you set up are
keep the dowels short as they add weight , plan your 4-40 portions carefully so that you get good smooth no bind exits but yuo also get good support ect .
This menthod has never failed even in very tight appliactions , you just need to plan the exist