What kind of panel do you have? If you have some big EFIS screens then you could mount the transponder on it's side and parallel to the length of the fuse. that way it will be removable when the EFIS is out. I did not think far enough ahead and could not do this. A slider makes it easier to do this.
I did not like the rear location for W&B - no numbers, just a long standing 7 tendency for rear CG.
It is big and awkward to mount. I laid it sideways and offset to the right for removal. I can get to it easily by sitting on the spar and "feeling"
Here is the top picture. It is on the right side below the two transverse rails. The antenna is just inside the air exit of the cowl just behind the firewall.
