If you have a laptop, maybe you could scan the charts? Yeah, it'd be a bit of a pain, but it's
definitely a way to bring them with you without being obvious that you have 'em.

You could even size the scans to be the same size as your screen, then set one to be your
desktop background. Set new backgrounds as you move along. Older laptops would be
great for this, since the older LCD displays are tough to read off centerline.

You could also convert the scans to black and white and reduce the contrast to the point
where the charts look like an abstract design or something. Or maybe no longer look
map-like at all.

Oooh! Even better. If you have a digital camera, photograph the charts. On my little 2M pixel
pocket camera, in playback mode, I can zoom waaaaay in. Again, not as good as having the charts, but to
an outside observer, you're just taking a lot of pictures. :-)