I realize you asked for a ruggedized laptop. However, that everyone else replaces theirs regularly points to the idea that you should consider that as a serious alternative and not discard it out of hand. I called this 'out of your box' because they're all doing it, and you're rejecting it a priori. I see basically three legitimate issues with this solution:
a) maintaining a consistent interface for you to be used to
b) providing easy data migration to the replacement device
c) total cost of multiple non-ruggedized devices compared to the realistic lifespan of ruggedized ones.
I'm not suggesting that my parent post had the right thoughts in mind, but Apple does provide surprisingly good, quick and easy solutions for a&b in OS X and the iPhone; I would expect the iPad to continue this.
Apple is not historically great about 'c', but that sand environment is hard even on the modestly ruggedized ones so it's not impossible.
Of course, I imagine their are
Of course you might need to account for shipping, purchasing, processing, or environmental costs in 'c', but even on the environmental front it's not a given that one device is better than 3, esp if it gets recycled well (many parts of the sandworn one will still work, and it'll be early enough that those, minus your HD, are reasonable used replacement parts in the right shop...)