Each year we organize a "centre of the year" poll, where users can elect their favorite centre. The winner gets the trophy for a year and users can enter a sweepstake where they can win a €25 coupon and a guided tour through the winning centre. The online poll is open for a month around a 3-day tradefair where users can vote as well.

For this tradefair voting I had a problem as we wanted the online poll to be active where we don't want an anonymous vote rollover, but authenticated user can only vote once.
For this year I just hacked a specific $uid into the code to make this possible, but I'm pretty sure that this isn't way to go ;-)

I think the correct way would be to add a permission 'multiple vote on decisions'.
I have approx 10 months to choose between hacking for next years poll or trying to build a proper solution.

So, any suggestions or alternatives for this?