Here is some exciting news - I finally installed the rubber feet! I bought them at Home Depot for a few dollars and they came with the screws.
Since I do not have a bottom panel the first thing I did was cut out some small triangles out of MDF and glued them in place in the back. I did not have to do this in the front because the panel here is actually 1.5" thick (2 MDF panels).
I just eyeballed the locations, drilled the holes and fastened the feet to the bottom. This may not seem like a big deal but it makes it so much easier to place on the table or wherever to continue working on it.
I also trimmed the t-molding to final length and fixed the slot in the back - it had broken off a little since the slot is so close to the edge (to compensate for the thickness of the back panel). It is solid now and looks great.