[eNyoron]

This question is probably best asked at the official Q&A, but if I'm missing something that makes the answer to the question blatantly obvious then I can trust that one of y'all would correct me.
Looking at <R18> in the manual, the requirements are pretty strict:
The trailer hitch must be in a fixed location on the robot, attached rigidly.
You must use the steel trailer spacer.
You must use the steel trailer mount bar, open side out.
The mount bar must support the hitch pin to which the trailer will be attached.
The horizontal center line of the Trailer Hitch must be 2-13/16 inches above the floor.
Contact must be bumper to bumper, not bumper to trailer tongue

But there's nothing explicitly barring you from constructing the hitch and robot such that the trailer will be locked in between your bumpers (two points of contact with the hexagon sides on either side of the tongue).

Having a non moving trailer in this low traction environment should significantly improve control the drivers have (no momentum to constantly cause the robot to spin).