I humbly suggest your transmitter isn't in an ideal position - having it directly in the center like that can make swapping batteries challenging with the antenna right there. That's also causing the trouble with the Zenmuse ribbon cable. I would either move the transmitter off center or turn it diagonally, make sure the antenna is towards the side WITHOUT the compass. That should both make the battery clip more accessible, and move the Tx cables away from the Zenmuse ribbon
I personally use 3M outdoor double sided stickytape, 2 layers and it's been holding my TS353 just fine. When I was running a TS352 which is much bigger and heavier, I backed up the tape with a harness made out of like 5 little zip ties... you know, connect them end to end (except for the one you do last after it's "installed") and just wrap the "harness" around the body and tighten it down. super cheap and doesn't really add any weight