If the air bubble is too much for you, what your going to want is a large rubber floor mat similar to the following:
http://www.sportsimportsltd.com/onepiecdurga.html
I use a 7X16 rubber floor mat to keep the humidity from wicking up through the floor. I used to have to re-detail my show cars every spring until I found one of these heavy duty rubber mats. An inexpensive solution to a simple problem. As for high humidity in the garage itself, two ways to go about things, either a dehumidifier for the warmer months, or "Desiccant Bags for the winter months.Both work equally as well for different situations...........
Bill S.