Thanks Airmann.
My thinking are along the same lines and I exercise extreme caution. 2000 below I still consider it a risk and up to 5 minutes after.
But this is mainly based on feelings and guesses rather than anything solid.
I really wished there was some study to say "a vortex can/cannot descend more than 2000 feet" or "The vortex of a A380 in cruise holds energy for up to 5 minutes".
I find it utterly bizarre that this is not part of a certification process for a new aircraft. It should be up to Airbus when designing the monstrosity to study how badly it will effect other traffic.