As a landlord I understand your logic of trying to make your application more attractive by paying so much ahead of time. To a landlord with a bunch of applicants it does add some measure of confidence (providing it's legal). So there is some value. If it isn't legal, perhaps a larger security deposit. All most landlords care about is getting long-term good tenants. Convince them of that and you'll be ahead of the pack. As for the suggestions of negotiating a lower rent, that's completely out of the question when it's a tight market and you want the place. The first thing the landlord is going to think is that you can't afford the place.

Edit: Another great idea would be to offer to sign a longer lease. That's attractive.