Nice set up but one thing I see that I don't think is going to work.

Is the tube hole in your box needs to be larger to allow it to get air in it. also where you doped the box that will stop any filtered air from getting in , Myself I don't think even a undoped box would allow enough air to get in with the tube as tight as it appears in the pic. A person dosen't want a tight fit on the tube, I use a pill bottle with the cap drilled for the tube to fit with slop and tie off the tube so it can't come out. All this is doing is moving the hole in the plate away from any high or low pressures the cowl or wind might make on it, in other word its a shelter from the pressures or wind.
I have seen several that just went to the inside of the fuse and ran fine, No box or bottle, However I like the pill bottle myself. I have heard of some going as far as the use of a condom in a bottle to get a air tight seal that allows only the air within itself to operate the diaphram I think thats going a little bit to far.