Hahah, you're right Bill.. the stress of having ANY box outside is usually enough, but having them stacked up was very harsh.
There are planks going from chair to chair the radios are sitting on and they didn't sit 100%flat too, which made things very iffy at one stage.
Prioritising the weight more than the size became the best rule to stick by, keeping the heavier ones as low to the ground as possible.
And another tip: make sure there's no wind!!
Rock On.