thx for the suggestions folks, keep em coming if you think of anything. I do run rows of fans starting in sept. One row mounted up high, and one row just above ground level. Even with that I lose many pounds each year.
The idea of enclosing the space entirely and running a dehumidifier would be very difficult, but not out of the question. I do have several dehumidifiers running indoors so it's not impossible. If I did that I feel like I'd have to figure out how to run at least a limited amount CO2 in there as well (several ways to do that, more annoying than difficult). I guess it depends on how busy I am that time of the year.