I have a big dryer/water trap on mine, must be about 4" diameter and about 8" tall. It is bottom drain, but since it is a horizontal it's not as effective as if it were on the bottom of a vertical tanked unit. I plan on getting vertical for space reasons as well.

The compressor I want, 19cfm at 90psi

One other thing to think about too. depending on the size of the space you are using for your shop/paint booth etc. you can take the compressor and mount it outside, or out of the way, and run hard line (pipe) to different locations with quick connects. really beats dragging a hose around everywhere. Just another thing to think about.

Red