Yikes... you really DO need to lower that humidity, don't you! Ok, so you're doing everything you possibly could - it's good to have an air conditioner outside the tent (I assume you have ventilation/fans going) and it's good to have a dehumidifier inside.... but obviously that's not doing all you need. There's a simple, cheap way to reduce the humidity - I just don't know if it will do as much as you need it to do.... Anyway, you take 2 5-gallon buckets... in one bucket, drill a bunch of holes in the lower 1/3 and the bottom (1/4"??) and the put that bucket inside the other one. Now get yourself some rock salt and dump it into the bucket with the holes... the salt will take the moisture out of the air and convert it to water which drips, then, into the lower bucket and you can take out and pitch... You'll probably have to monitor the water level in that lower bucket frequently as you don't want it to rise and start getting the rock salt submerged!
Good luck.... in six months, we'll be trying desperately to keep our tents warm and humid!