I kinda like your idea of 2 outputs with a "blank" one. A possible issue could be that it would not be doable with all clients. Much organization would be needed...
Yes, I was just trying to design a transaction that would be considered "standard" by the reference client. More exotic designs (such as having multiple OP_RETURN outputs) would be difficult to propogate.
If you want it to be so that a vote can be cast easily by most/all clients then you have more of a challenge. Without some coin control, the voter would have no easy way to tie his wallets balance to a particular vote. This will basically be by design; good wallets protect the user's financial privacy by default. With coin control, a user might replace the OP_RETURN output with a regular transaction, burning a small number of satoshi to a special voting address. The number of satoshi burnt would correspond to the choice of the voter. Expect to meet resistance with such a proposal though as these voting outputs would not be "provably unspendable", tantamount to an attack on pruning nodes.
I've thought of coin control. That was one of the reason behind the choice of a speedy vote. No more than 24 hours, with voters making the pledge not to make any other transaction during the allowed voting period.
I guess this isn't going anywhere, though. I was looking for a way to solve the blocksize issue, but my idea hasn't had enough support so far. When I look at all the posts on this topic, there is clearly more people against the idea than there are supporters. Well, it was worth trying.