AC
Your idea, whilst novel, assumes an attacking missile will come from the rear hemisphere.
If an aircraft is traveling at a decent speed the ‘balloon’ would need to be truly enormous to cover even the rear aspect.
Most missiles will plot a collision course with their targets and, hence, will not come from behind.
As an aside, can I be the first to offer up ‘MISDEMEANOUR’ as the unofficial name of the MSDM?
BV