[freeloaderz]

It's likely I misunderstand but using the GPL essentially prevents contributing or you lose the ability to dual license (without a CLA)?

The intent of the clause is to encourage both, if you contribute, you can do whatever but maybe it doesn't work that way.

[rglullis]

I think your understanding is correct, but I don't see how asking for a CLA is too much of a problem. It's at least more straightforward than whatever legal spaghetti you'd be getting into just to find something that fits your definition of "fair".