Large mesh feeder for sunflower hearts?

We feed sunflower hearts and can get through 10kg a week at busy times but I'm wondering if there is any solution to the problem of the hearts getting soggy and clogging up the bottom ports. We've just got a large  new feeder with twist off ports and base that certainly makes cleaning easier but I've noticed that it seems more prone than other feeders to clog up.  My attempt to shake the offending seed out resulted in the bottom dropping off .........

We have some mesh feeders about 30cm high that are ideal for hearts but get emptied very quickly and I'm wondering why the manufacturers don't make much larger mesh feeders - this would make the seed accessible all the way down and solve the clogging problem.  

Is the answer a rain guard on the top of the feeder - or fixing two or three of the mesh feeders together? Or perhaps we shouldn't live in Devon where it seems to rain more than most places............

Any thoughts/experiences gratefully received.