If the feeder is big enough, could you put a heavy stone in the middle? I have also dug my outdoor "slop pan" into the dirt just a bit. Sometimes they knock dirt into it, but I just tip it over, tap it to empty it, and put it back in it's "nest." Inside the coop, I use piglet feeders as they hold about 3 big coffee cans of food and NEVER clog up or spill. You hang them on the wall and they are kind of compact, saving alot of floor space. Not much "beak room" though (the trough is only about 8 or 10 inches wide) so you may need to buy more than one. My gals seem to take turns at the feeder pretty well, and I usually have some feed available outdoors in the run if the weather is dry. Good luck!