Thanks Zeeb for setting the point. I couldn't find any photo of my tube rooting, but I think to remember that I passed servo cable and 3mm tubes through the spar just over the wing tube (about where the wheel opening is). As I use the MPX plugs to connect servos, I always cut off the original servo plug and as normally you also have to extent the cable, getting throug these small openings is no problem.
Zeeb: nice scheme,
here is mine from the 2.5 