All of the above is good especially for the controal surfaces. A good test is to grab the controal surface by hand with the radio OFF, and flex it. If the servo turns without deforming/flexing the pushrod, its stiff enough no matter how long it is.

As far as the throttle linkage tho there is another way. If you have a "Z" bender and some single-strand wire like mechanics or bailing wire. You can make a "z" to connect to the throttle arm, then bend a larger "Z" into it to get around whatever is in the way. Drill a hole in the firewall that fits the wire and run it back to the servo arm and connect it with another "z". (The wire must be supported by going through the firewall and bulkhead to the servo.) You can bend as many "Zs" as needed to get around the fuel tank etc. Adjusting the length is nothing but bending a "z" tighter, or looser. The wire will hold its shape, and since its relatively soft, won't hurt the servo in a crash as it will just bend. If electrical noise is a worry for you, use a ball-socket connection on the throttle arm and solder the brass piece to the wire. A 90deg. bend can be made from there to get around the obb-stikle. I would not hesitate to go metal-metal though. The ball-bearings inside the engine probably make more electrical "noise" than the wire/throttle arm would. JMHO. Others could advise on this better than I. Hope this helps! Q.

edit; Get a "Z" bender if ya don't have one! Its one of those gizzmos that ya never knew how bad ya needed, til ya have one!