i would try a lanyard or case (looks a bit lame) or you can always try a smaller 650mah battery, as far as tank wise maybe try T2's or CE5 something small with a stable metal binding.
Right now i've favored a lavatube v2.0 , but i think the most durable battery i've had is my old ego-t 1100mah it's been a long time and it's fallen way too many times :P