It's here! Though I'm not sure when I will be able to try it--maybe tomorrow. My bike is already loaded up in the back of DH's vehicle for our ride tonight.

Looking at it I'm immediately struck by how shallow the relief channel is...it looks deeper in photos. I sort of suspect that it may not offer much actual relief, unfortunately. It should be obvious pretty much instantly if it's not going to work. The overall footprint is wonderful, though. So VERY t-shaped!