We used shims on my ASW-20B to eliminate the slop.

On the '20B, the fore and aft pins in the fuselage can be knocked out
using a steel rod through a hole in the pin on the other side, and
gentle tapping with a hammer. Thin metal shim "washers" were installed
until the clunk went away.

Fly straight at 60 knots and wag the rudder slowly. If there's no
clunk, then slop is gone.

Beware, on some ships (PIK-20D) the spars and carry through tubes have
different coefficient of expansion. If you get rid of the clunk on a
cold day, you may never be able to assemble on a hot day. In this case
you can't completely get rid of the little bit of play.

Also, the gap between fibreglass parts on fuselage and wing is really
inumportant - it's the gap between the metal parts. That's why we have
tape!

-Tom