The bolsters seem to be plastic, so I'm going to try to remove the raised ring around the screw boss. With luck, a chisel blade will work, slicing down multiple times around the boss, then flat against the bolster to remove the pieces. A little filing with a knife-edge file might be m=needed for cleanup, but it shouldn't be too big a job.
It seems like someone must have misread a drawing or something. I wouldn't think that, as much work as Athearn obviously put into these cars, they'd intentionally design them to be too tall, especially since the fix seems so simple.
Mine don't have sound, so that isn't an issue, and I don't have any BLMA 100-ton trucks. Guess I'm going to have to order some direct one of these days, since my hobby shop can't seem to find them. I need a pair for a tank car kitbash from months ago!