Don't bother trying to pick them up yourself, I watered my lawn at night for 3 hours straight the other night, when I went out to pick them up I saw nothing and when I started digging the ground was dry about 3 inches down!
This is not a obvious choice but what about a topper? they can handle slightly bigger water, if you get the smaller sizes they weigh about 80lbs, you could fit it into a storage locker, you can get it on a roof, they sell them at bass pro for $500.