This is a classic catch-22. RH is ok, but temp is high. Add ice which adds moisture, RH out of control. Add dry ice which drops temp, but will also drop RH and displace oxygen with carbon dioxide. The only real solution is to put the humi in cool place. I have virtually ignored temp in my cabinet for years without an issue. 70's or even 80's won't hurt your cigars. The higher temp will stimulate beetle eggs to hatch swarthy, thin mustached, tobacco eating bugs. So many manufacturers have taken to freeze killing the eggs, that I haven't seen one in a long time.