I think the best system I've seen so far was the one used by the
Cable Company on their two-tier forward facing pneumatic stacks.
They used a paper gasket with a hole in it about 1/4" larger that
the corresponding hole in the deck board and the pneumatic itself.
That way you have a ring of wood-to-wood contact right around the
hole which eliminates possible leakage.

To ensure that the pneumatic wouldn't pop off under heavy pumping,
they punched two additional holes approximately 3/8" diameter in the
gasket, one near the front of the pneumatic and one near the hinge
end.  When gaskets like these are used, they will come off the deck
with virtually no damage.

For my gaskets, I use the paper tape used for taping drywall seams.
I use hide glue to attach the gaskets to the deck and then go over
them with a warm iron to make sure they are perfectly flat.  You can
then glue on the pneumatics with hide glue as you normally would.

Greetings from the snowy Oregon Coast!
Regards,
Bruce Newman