I set this up with my chickens yesterday in a 5 gallon bucket. My god they make a big mess and waste a lot of food on the ground.
That surprises me. I have had one of these PVC type feeders in a 5-gallon bucket hanging in my coop for over 4 years. It's not 100% waste proof, but much better than other feeders I have tried. I have my feeder bucket hanging about the level of their backs, so the chickens have to reach into the PVC to get the food. There is not much waste at all.
I know some people have installed the PVC ports upside down, and then the feed would just come pouring out. But if installed correctly, you should have very little spillage.
Like
@TooCheep mentioned, please post some pictures of the feeder setup. I would also request a picture of the inside of the feeder showing how you installed the PVC ports. If you are getting a lot of waste, there must be some reason and maybe we can see something if you post a few pictures.

There are over 400 4- and 5-star reviews on that product. There were only 2 1-star reviews I could find related to food waste. However, if you bought this kit from
Amazon, you can still return it for a refund and put in a negative review on your experience with the product. FWIW, I would not have recommended this product if I had poor results. But I could not be happier with the performance of my 5-gallon PVC bucket feeder. It dramatically cut down my feed waste.