I'm fond of the Pelican brand environmental cases sold to protect sensitive devices, like cameras, electronics, guns, etc. I used one on my Yamaha FJR1300 for several years, with great success. They are water, humidity and dust-proof. Perfect for cameras and laptops. My friend Greg, who uses cases like this daily in his profession, prefers Hardigg's Storm Cases, which he says are a bit cheaper and have better latches and an automatic pressure vent. The same mounting technique I describe would work for them too.
This time I bought two cases, a model 1520 and a model 1400 from 4LessDepot.com (formerly Cases4Less.com). They have great prices, and even better service and shipping. I bought two cases because I wanted to use a trick my friend Phil told me he'd seen where a smaller case (the 1400) was mounted on the lid of a larger case.
My goal was to have a locking mount, that ideally used a single key. My friend Steve suggested buying an "R1200GS Solo Mount" plate from Jesse Luggage Systems, instead of making one as I'd planned. I did, and it was just what I was looking for — plus it locks into the stock passenger seat lock, so I can use the ignition key to attach it!

The photo above shows the Jesse mount plate bolted to the bottom of the Pelican 1520 case using the hardware supplied with the mount plate, plus some 1/4" aluminum spacers I had left over from other projects. The whole mounting project would take only about 1/2 an hour if you didn't have HID ballasts to relocate. I came up with a trick to increase the under-seat storage capacity in order to relocate the ballasts.

The only problem I encountered was that my Jesse mount plate was poorly made, and doesn't slip into place as nicely as did the stock seat. From the photo above you can see the problem. The two locking ears (which fit into the stock holes where the passenger seat fits) should have a slight inward orientation at the rear, shown by the direction of the two arrows. The one on the right was perfect, but the one on the left was drilled and mounted (then powder-coated) in the wrong orientation. That makes it a bit tough to line up and get it inserterted, but it does work.
I'd have fixed it already except that the entire plate is powder-coated, covering the mounting screws on the reverse side, so it would be a bit of a project. I'll decide after winter is gone and I can ride again whether or not to try to fix the mount.

Attaching the smaller Pelican case to the lid of the larger one was quite simple, and required only that I buy some 6 x 35mm allen-head bolts. I centered the two cases, one on top of the other. I thought about aligning the smaller one's leading edge with the leading edge of the larger one, so I could use them as a back-rest. But I tried it and didn't care for it, so I opted for the symmetrical arrangement.

The inside lid of the 1520 case, with the foam removed, showing the mounting bolts.

The end result. With the big handle on the larger case, it is actually not bad to carry — it isn't as lop-sided as I thought it might be. It rests nicely against my leg when walking with it.
I should mention that the Pelican cases have two pairs of tabs suitable for a padlock, in case I want to leave the bags locked on the bike as well as locked closed. They also have a pressure-relief valve (the small bit of red under the handles) so you can get the lids open in cases where the air pressure increased since you closed the cases. Yes, they are that air-tight!

How it looks when mounted on the bike. The width of the 1520 is perfect so as not to interfere with the stock saddlebags. I plan to mount a Roc-Strap over the leading edge of the larger bag as added security, in case the lock fails. I can easily slip it aside when I want to open the case.

With the lid open. Of course I'll want to be DAMN SURE the lid on the camera case is closed and latched before I open the bigger case! You can see the pick'n'pluck foam in the larger case as it came from the dealer.

A shot showing how far the case extends to the rear.

Looking down into the 1520 case (handle is at the top) showing my 17" Dell laptop surrounded by foam padding. Lots of room on top of the laptop for other stuff.

A final shot showing my Canon digital SLR mounted in the 1400 case along with a small prime lens, spare batteries, a polarizing filter, spare CF memory cards, and a battery charger. The piles of foam are the pick'n'pluck pieces I pulled out to fit the camera and laptop.
Follow-up
Someone asked how much this all cost, and the answer is about $250 (US) including tax and shipping for the two cases and the mounting plate.Copyright © 2006, by H. Marc Lewis. All rights reserved.