Here's my thoughts and take it for what it's worth....
I've always struggled w/ high humidity (70% and up) and I've tried to take several steps to reduce it but nothing has seemed to work with the exception of decreasing the surface area of my water dish. Even then, my hygrometer still reads in the 70-80s most of the time. I've spoken with some breeders and other 'experienced' herpers and they didn't think it was so much of an issue as these snakes are used to a tropical area where humidity is extremely high. As long as they are not sitting in wet substrate, I think you should be fine. I think lower humidity is more of a concern. Just my two cents.....