I checked a large bag going to sim training as well, and didn't need it. I could have gotten away with what I could pack in a rollerbag and flight case. Don't waste your time (and weight) carrying your Jepps, FOM, PSM, Airport Directory, or any of your ground school binders. Bring your POM to study the profiles and procedures, the gray Bombardier book (PRM) for systems study, and your cockpit poster for flows practice. Anything else is unnecessary. Your hotel will have laundry, so just bring 5 changes of business casual clothes and 2-3 changes of casual clothes. Use the extra space in your flight bag to bring along a laptop or other extras. Otherwise, everything you'll need for sim training will fit in a 22" rollerbag if you know how to pack it.