RE: Fiberglassing wing panels together
The reason you have bubbles is most likely the surface underneath had something contaminating it (finger oil, etc ). For future reference, before sanding go over the area with a DAMPENED (not wet) with alcohol. After the alcohol dries, sand the area, then remove the dust by using an air hose, brushing it off, etc. THEN go over the area again with a cloth dampened with alcohol.
The suggested way to do a re-enforcement of the center section is: Put down a 6" - 8" wide strip of 2 oz fiberglass cloth, then put your resin on the cloth and work it into the cloth (get rid of the excess using rolls of toilet paper or an old credit card or a combination there of). Do one side at a time AND LET IT DRY BEFORE DOING THE OTHER SIDE. After you have done both sides, lay a strip of 2 oz cloth that is 2" NARROWER than the first piece over the 1st piece and apply the resin and remove the excess. This time take a piece of Saran wrap and CAREFULLY put it over the resined area and GENTLY press it onto the resin and smooth out any wrinkles/bubbles. Secure it down with some masking tape. When dry, repeat this for the other side.
The Saran wrap makes the drying time a little longer, however when you peel the Saran wrap off the surface will be smooth and require little, if any sanding. Go over the area with a cloth DAMPENED with alcohol to remove any wax. Now use some lightweight filler to feather the edge of the glass into the wood and the edge of the 2 pieces of fiberglass together. This will provide a smooth, barely detectable re-enforcement.
In your case, I suggest filling the bubble holes with light weight filler and sand everything smooth. Then apply a second piece of 2 oz fiberglass cloth as described above and make sure you use the Saran wrap over it and finish as described above.
Finishing resins typically leave a wax residue on the surface when it dries.