Chuck's Gold Trapper Options

[RichDColorado]

I saw a few threads on Chucks Gold Trapper and they were pretty favorable. I was traveling in Wyoming on business this past week and on the way back I called Chuck and stopped in to buy one. Very nice to meet the gentleman and I did purchase one of the units. A question I have is about rocks getting trapped/stuck in the flap. A friend has a Gold Trapper and said he noticed rocks getting stuck in the flapper from time to time. The flapper diameter is 2" and the extension tube is 1 1/2". Has anyone tried putting a smaller screen over the end of the larger tube or the extension, maybe 1/2" or 1/4"? I thought that may help to classify a bit to keep larger rocks from getting through. Also, if classified down to the smaller size it would be better to run it directly through the sluice from the Trapper.