Good grief- that's a lot of holes and still getting high humidity!!! Your tubs look a lot like mine and the only think that I can think of is to use a different water bowl. Yours has a wide surface area; can you find something with less surface area? This will cut down on evaporation.
Also, how bout if you set it down lower to the floor? I have my racks on a low table 14" off of the floor. Maybe lowering your rack will help with the heat and the humidity, since both tend to rise.
Additionally, it looks as though you have different numbers of holes in some than in others. Could this account for some of the temp and humidity difference?
Lastly, have you had the chance to adjust the t'stat probe? Let me know how that works!