[GaryVoshol]

Based on a lot of posts here and several official Q&A's, the answer isn't simple. You may not touch a trailer except bumper-to-bumper, that is clear. You also may not extend any part of your robot outside the BUMPER PERIMETER.

Team Update 2 had a diagram in it showing what the GDC thought was the maximum incursion a trailer could have into a robot frame; based on that diagram you would not be able to enclose a trailer enough to be able to shoot straight down into it.

If you've figured out a way to do it without violating bumper rules or robot-to-trailer contact rules, good for you.