Qdeathstar:
I think you will be fine just powering the strips (and associated 485s) on one end of the structure. I would not power both ends of the structure because you may introduce ground loops into the system. I wouldn’t ground both ends of the structure for the same reason.
OK, I'll try the changes in the days to come, I also will use thicker wires for power (I checked and they're a little thin, so that should be one of the main problems).