I flew a Vulcan at 300 ft and 350 KIAS over a 'feed lot' in Kansas once, 411A - that got a few thousand cows galloping about!
Light ac have no reason not to fly below 1000 ft; it's those which operate below 500 ft who put themselves at significant risk from military low level activity.
However, mil aircraft operators should also accept that the levels between 1500 to 3000 ft a.g.l probably contain the greatest numbers of light GA aircraft - and hence pose the greatest collision risk.