I have used my new UV box a couple of times and can now provide some feedback.
My design involves a 2x3 array of bulbs on 6" centers, with the tip of the bulb about 6" above the glass surface of the contact frame. The inside top of the box is lined with aluminum flashing. My limited experience is that this produces even illumination. I included a small fan in the box, and preheat the bulbs for 30 sec or so before starting an exposure.
I have chosen to start the alternative process adventure with VDB, and have had two printing sessions so far. For the first, I used a single application of sensitizer on Stratford Bristol paper. I got decent (but unexciting) images with exposures in the range of 12-15 minutes. In the second session, I used two applications of sensitizer on Aquarelle paper. I don't know much about this paper other than it has a relatively smooth surface, but appears to be fairly thin. This time, the exposure had to be about 20 minutes. In both cases I was using 4x5 negatives (but not the same negative in both sessions).
The conclusions so far:
1. Choice of paper is very important, with thicker, more absorbant papers working better than either thinner papers or very smooth ("bristol") papers. This morning I purchased some fine grain Aquarelle cold press water color paper that I think will work better than the thin stuff.
2. Double coated applications (per Wynn White's article) seem to work better than single-coat applications.
3. I'm using in-camera negatives, and selecting negatives that are marginally contrasty for traditional enlarging/silver printing.
4. I prefer selenium toned prints to non-toned prints. I know that selenium toning tends to bleach the image, so I have been careful to use very dilute selenium (2 ml per liter of water) and limit the time in the toner bath. I think I need to print darker, and then let the print stay in the toner longer to get the result that I prefer.