Oh, yeah! :) !!
1. I choose the first way.
You should provide the cable with every FMB unit with OBD.
I doubt every vehicle has enough room under such a lid and every end user will be able to find the cable.
Take my stupidity as an example. (facepalm)
2. No. It won't help. Removing the case will barely allow maybe just a half of the distance for the lid.
I doubt every end user will accept the open electronic guts of the device protruding from OBD socket.
Thank you for your support!