Lewm: "if I was still interested in belt drive for my own use, would be two motors positioned at opposite sides of the platter, 180 degrees apart, so as to equalize the forces involved in rotating the platter through a belt connection."
I would simply placed another pulley next to the platter on the opposite side of the motor: one motor, one platter, and two pulleys. I think that would do the trick without the extra motor noise. VPI did something similar in their early TNT model but with THREE pulleys!