This is my first instructable, so it probably won't be so great. And my drawing skills are not good, but here it goes. For this project i wanted to be able to have a skateboard that i could fold up into a suitcase or some small case, store in my backpack after skating to class, then whip it out after class, assemble it quickly and be on my way. I tried many different ways for the foldable part to work and well basically failed many times, spent more money than you would believe on that, so thats still in the works (let me know if you have any ideas on how to get that part to work). But in this process i found a pretty useful way to attach trucks to a skateboard, which allows for easy changing of trucks and wheels, and i've found works just as well as nuts and bolts but is 20x faster for changes made once set up and leaves the board still very functionable compared to a standard skateboard (the boa dials could get messed up from boardslides ect., but if your good nobody really slides that part of the board anyways)
It's a cool idea - but as far as class is concerned... We just lean the board against the wall by the door or put them next to our seats :P But then again, Engineering professors really don't care too much when it comes to things like this (and attendance for the most part :P).
As for this design.... I'd be concerned about the boa reel itself. They are designed for laces on shoes and boots - things that don't see such a load. Sure the site says "bet you can't break one" which to me, sounds like a challenge. Of course, "concern" means test the sh!t out of it.
Would the folded height be too high if you left the trucks attached? Here is what I'm thinking - leave the two inboard bolts attached. Then cross the boa cables over and then into the boa reel. I really don't know what shear force those bolts are under so I can't help you with figuring out what you'll need to keep it stable....