I believe what you are seeking is a better way to achieve smooth
wingskins. I will propose two methods which have achieved varying
levels of success.

Method One:

Per the late aircraft designer/builder/pilot/writer Alex Strojnik,
outlined in his book, Low Power Laminar Aircraft Technologies, lay up
on a sheet of plexiglass, when the skin has partially cured peel it
off the plexiglass and place it over the wing smooth side up, stretch
another cloth - not fiberglass - over the wing weighting the
overhanging edges until the skin cures. He used about 40 lbs of
weight total on 4 foot sections. Strojnik claims this will work,
given practice, three out of four times. His idea of "working" was a
skin with virtually no defects, correct to "within 0.01 in." Your own
idea of acceptable might be much more reasonable. He also cautions
that at first it will work only half the time. Again when he says
"work" he means virtually perfect skins. He used this method to
produce d-cell leading edge skins continuous from upper spar to lower
spar. His d-cell was pointed toward the ceiling when he formed these
skins. He bonded them after forming them.

As another poster pointed out, it is the leading edges which is most
important.

Method Two:

Perform a normal layup directly on the wing, cover the wing with mylar
sheet, bag the wing, apply moderate vacuum until cured. This method
works very well on smaller sections and can work with larger sections
if they are accurately formed and sufficient care is taken. Among RC
modelers this method produces consistent mirror like finishes with
very little sanding.

The two most important factors to achieving a smooth surface a

A smooth underlying surface.

A smooth surface contacting the outer surface of the layup while it
cures.

Any method that manages to create these two things will succeed. It
would be prudent to experiment with these ideas on smaller test
sections to hone your skill before doing a "real wing".

Fly right.

nc