Sight down the tail boom to verify and correct the squareness of the
vertical tail before the glue sets.
The easiest way to mount the fuselage servos is to glue them to the
fuselage sidewall. In case you need to remove the servos later (for
repair), wrap them in masking tape. This way the tape can be cut
later and unwrapped off the servo, and the servo popped out.
You can use an optional plywood base glued to the fuselage
sidewall, for protecting the fuselage in case of future servo removal.
This also provides a flat surface for gluing the servos.
Servos are glued to the plywood base with medium CA or 5-min
epoxy.