Filament Guide for Lack Table

I'm in the process of creating an enclosure for my prusa i3 mk2 and I've gone the lack table way that seem to be popular. I've been looking at all the different filament guides, they seem to be mostly small holes or long narrow holes. Both make sense.

I'm going to be bringing my internal height of the enclosure up to 18" with the addition of printed parts that double for holding the acrylic sides in place. I've been told that the small hole would be a detriment to taller prints so the long hole would work better. This is where my idea came in, with the wider cone base that goes on the underside and the small hole at the top the pivot point of the filament is raised an additional 1.5" which should be enough with the extra height of the enclosure to allow for a small hole right at the top. At least that's my theory, still to be tested. I wanted the small hole to keep the ABS vapors in the box as much as possible.

I designed the bottom for a 2.5" hole (cause I have a hole saw bit