First, I think your plan is crazy in general. Those items have precision moving parts and they aren't going to handle the jostling of such a trip very well. They may never work as well again. If possible try to repack them exactly as they came delivered (that usually means putting pieces of styrofoam INSIDE the printer).

But if you insist on doing this, you might want to try leaving from a city where the baggage scanning pods are out in the public area so you can watch as it is inspected and needs to be opened.