Need Two Phones/One Line - Sim-less solution?

[KevinTernes]

I really need two phones but I only want one number/line.

I need/want a smart phone. But I also need a ruggedized phone like the GzOne that I currently have with Verizon. Given the nature of the way I play, I need a phone that can take being immersed in water and get banged around against rocks.

I was about to make the switch to a carrier that uses GMS and Sim cards so I could buy an iPhone or something as well as a ruggedized phone and swap cards depending on where I am going.

But now the Droid is about to come out and I want it.

Is there some obvious solution that I have not thought about whereby I can have a Droid 5 days a week and easily switch to the GzOne 2 days a week without paying Verizon for two lines?

Keeping a Droid buried in a bulky, padded dry bag would not be convenient.

Thanks.