BRL
That is sort of how it works. Actually the erratic flying bit is not really required because ou don't normally get spotted. YOu can choose how erratic you want to be depending on how much you are keen to save the cost of breakfast.
Most stick with normal manouvres but either a low routing or a high routing to avoid being seen.
We don't go for full reg just type and colour so we don't need to get closer than 500ft (i think the 'proper rules' require reg as well but we don't).
We have had a Pitts playing the Battle of Britain bit to out manouvre the spotter but this is not a requirement!