Aileron linkage: Sullivan cables running through ribs into the bell crank. Linkage is totally slop free and with zero binding. Use of dual servos for ailerons is quesitonable, since a single servo seems to be more than adequate for the job, but hey, better safe than sorry.
With the above setup wingtips are kept nice and light.

Coming up next, sheeting the entire undersurface of the wing. I'm going ahead with Luke's (dionysusbachhus) idea of sculpting the bay doors. Monokote the sheeted underwing and glass over it.