I took a look at mine. It'll be easy to fabricate something that's just as good and also customized to your dimensions. For the main board, get a 1 inch sheet of plywood. You could paint it or something for appearance.
If you notice the holes in the base of the column, you'll see they're at an angle. Cut four holes in the baseboard at the center back that align with the four holes in the column's base. Under the baseboard, position two 2x4's so that they extend in the same directions as each pair of holes. (They will fan out from the center back towards the two front corners of the baseobard.) I would position them so that the "2 inch" side of each 2x4 faces the underside of the baseboard. Then, screw four heavy duty screws through the column base, through the holes in the baseboard, and into the two 2x4's. You'll probably need to drill 2 holes in each 2x4 to receive the two pairs of screws.
Or, any variation that better suits your needs.