Heres my off the wall idea. Use tires or something like the "LIVE strong" and "VEX" wristbands just on a bigger scale, and make square or rectangular goals in the center that are elevated 7 and 10 feet off the ground. (3 goals, 2 7feet 1 10feet in the center) Have a 2 foot tall gap under the goals so teams could go under the bridge. Have 5foot tall goals at the red and blue alliance home zones. Still have it 3vs3. 1 Autoloader per alliance and have a suspened "tire" hanging on a hook on the side of the field with a green panel in the center (similar to this years vision tetra) for the CMU. Also, have a human player area with a 3'x3' box on both sides to distingush the "loading zone".
My paint drawings can be found
here
-KL