As far as the rules go, the attachment is actually considered to be a part of the robot itself when it comes to launches. Short answer is, yes, all of your equipment (robot + attachment) for a particular launch must fit entirely in base.
D03 - EQUIPMENT “Equipment” is everything YOU BRING to a Match for Mission-related activity.
D04 - ROBOT Your “Robot” is your LEGO® MINDSTORMS® controller and all the Equipment you’ve combined with it by hand which is not intended to separate from it, except by hand.
R10 - HANDLING DURING THE MATCH
• You are not allowed to interact with any part of the Field that’s not COMPLETELY in Base.
Except: You may Interrupt the Robot any time.
Except: You may pick up Equipment that BROKE off the Robot UNINTENTIONALLY, anywhere, any time.
• You are not allowed to cause anything to move or extend over the Base line, even partly.
Except: Of course, you may LAUNCH the Robot.
Except: You may move/handle/STORE things off the Field, any time.
Except: If something accidentally crosses the Base line, just calmly take it back – no problem.
• Anything the Robot affects (good or bad!) or puts completely outside Base stays as is unless the Robot changes it. Nothing is ever repositioned so you can “try again.”
R13 - LAUNCHING A proper Launch (or re-Launch) goes like this:
• READY SITUATION
– Your Robot and everything in Base it’s about to move or use is arranged by hand as you like, all fitting “COMPLETELY IN BASE” and measuring no taller than 12 inches” (30.5 cm).
– The referee can see that nothing on the Field is moving or being handled.
• GO!
– Reach down and touch a button or signal a sensor to activate a program.