[Al Skierkiewicz]

I think you will find that the answer to your question is in the starting configuration rule. One robot in each section touching a specific boundary when the match starts.
I am guessing that when you ask this question of the GDC, the answer may come from an interpretation of robot. If you drive around with another robot on yours, it could be considered one robot and as such exceeds weight, and likely size. Even if that still doesn't throw a flag, any contact with the second robot and another robot can only be in the bumper zone (of the bottom robot) and would likely garner one of the myriad penalties.

<G08> ROBOT Starting Positions – Prior to the MATCH, each TEAM negotiates within their ALLIANCE to select one of the three starting areas for their ALLIANCE.
When the FIELD is viewed from the ALLIANCE STATION, the ROBOTS must be placed on the right side of the CENTER LINE in one of the following starting positions:
• In the far ZONE and in contact with the ALLIANCE STATION WALL and/or ramp.
• In the MIDFIELD and in contact with the farthest BUMP.
• In the near ZONE and in contact with the nearest BUMP.