My suggestion would be to try and find some Deep Cycles without the acid added, the shelf life if almost forever. When your ready just pour in the acid.
As to life, think about your car. You start it anywhere from 2 to 50 times a day. Each time you start it you discharge the battery and the alternator recharges it, your car battery lasts for 2-3 years and it's not even a deep cycle although I'm running twin deep cycle marine starting batteries in my truck because the grid heaters on the engine drain a normal battery quickly when it's -10 and they have to by cycled 5-8 times.
Also DO NOT store the batteries sitting on concrete. Put them on a piece of wood. I've experimented and found that a battery on concrete is dead in about 1 week vs on wood blocks still at 90% after a month.