OK, here is another idea I just came up with.
Yesterday morning, a family member called me and said that he had found a 3 phase, 6kW variac--virtually unused--at a surplus place for $75. I had no clue what to do with it, but for $75, I told him to pick it up for me.
So would a variac with the secondary hooked up to some large, cooled power resistors work as a variable AC load? I've got nothing else to do with the thing...