Rear brake caliper already touching trainer before tightening

Hi everyone, 

I just bought the neo 2t today and it is fitted with the 142mm spacer. 

I'm riding a bianchi xr4 with sram red. While placing the bike into the trainer, the brake caliper is almost touching the trainer and it pushed against the trainer when I started tightening the thru axle (won't dare to ride on it)

Pls advise if I can/should change or add spacer, and by how many mm? Too less might still touch and too much might damage the seat  & chain stay right?