To sheet the second side of a fully sheeted built up wing while it is still in the wing jig?
still in the jig both sides is not practical, will surely lead to poor glue joints, probably warps and ugly butt joints.
my sheeting method is: build up the whole wing on the jig or with the bottom tabs still attached to the board and to the ribs.
sheet LE/TE add the capstrips and as much of the center sheeting as possible. usually i already have bellcrank already attached.
cut loose from the board, add a spanwise lenght of wood or aluminium bar to support the TE (not tapered). then add shims to the last ribs under the spars to raise them to the proper alignment with the centerline of rib 1. (means both ribs centers are paralell and same distance from the board.
then i do the sheeting and capstrips. what ultimately prevents the wings to twist are the capstrips.
as a method for glueing: capstrips i use CA. for The TE titebond and a long metal bar over it. for the LE: i fix the sheeting to the front spar with CA. then spray windex(that stuff for glass cleaning) on the outside of the sheeting. While it softens the sheeting, i run titebond on the ribs. when the sheeting is ready to be curved due to the windex action ( not dripping just a bit is enough) i run a bead of CA on the main spar and with a metal bar i slowly works the sheeting over the ribs to the spar direction, then gently press over there for the final bond. no need to do extra pressure, to avoid warps. this wau i donīt need any pins, clamps or packing tape to hold anything and the wings finishes pretty fast and true.