Bob,
A paint booth would work as long as you have great airflow through the hulls. Your not trying to bake the gelcoat but cook the composite.
The wax I use held up for an entire Florida summer! So I think it would work down Island.
One thing that you want to know both of my boats have two ports a hull one forward and one aft. Between the beam and the daggar trunk and aft of the rear beam.
I tried a fan up in to the hull once but didn't see any real difference you might in a paint booth since the heat is from lamps versus a radiant source.
Steve