The simplest solution - Inner Cover with an additional entrance-ventilation hole (1" X  3/8") in the front block/border.

 Some beekeepers like to move the outer cover back about a half  an inch.  The telescoping cover sits on top of the front of the inner cover. But sometimes it is not enough, especially if your hives are in a hot climate. Personally, I don't like this idea, especially if you have ant colonies near your bee yard. The second disadvantage of such approach is stimulation of robbery by local bees and a possibility of diseases transmission as bees from neighboring colonies can visit your hives without problem.  For my hives I have been using my Temperature Humidity Self Control Units since 2003  and have installed these units in 20 hives.

Durable Hive Stand with Ventilated Bottom Board. 

The Ventilated Bottom Board has a mite screen and an inspection/clean out drawer. The Hive Stand has reversible  wet/dry deflectors that can be filled with oil or water for         ant control. The legs elevate the hive off of the ground.    Plastic components are made with Hi-Impact Resin for  durability. A UV Inhibitor for long life. The plastic is     paintable for personalized colors. Plastic mite screen is removable for easy cleaning. A slanted floor directs  debris to the cleaning drawer/trap. Weight capacity is over  1000 lbs. Available in Green only. Shipping weight is 10 lbs.  by  Dadant & Sons

 "Ventilation is very important to the health of the hive. It can be             especially important in the winter in colder climates as well as during        the heat of the summer. We have found an upper entrance so moisture can  escape the hive in the winter combined with insulation so the moisture  does not condense on the underside of inner cover and drip down on the cluster significantly improves overwintering success.        Developed over several years, we feel out all season inner cover provides not only appropriate ventilation and insulation  during the winter, but also allows easy access for late or early season feeding, plus the benefits of passive cross flow       ventilation during the summer without the cost of other    systems."  by Honey Run Apiaries

 "Our Modification kit is an add-on for the standard hive, for the bee keeper with a number of hives who wishes to improve on the Langstroth or the standard North American hive. Independently tested, increases production and hive products by 85%. Cover is plywood rather than masonite. We have found  that the shiny surface of masonite will sweat and the water beads up. In Winter the condensation freezes and in the Spring melts and eventually this condensation will drip back into the   cluster. It is cleated to provide bee space on both sides and mesh covered holes provide ventilation.