A clarification to Stiknruda's post.
A DA does not waiver you from the 500' rule. For that you need a Rule 5 exemption from the CAA - and anyone can apply for one. But, if you are in a remote location you may be able to come below 500' (if you really want) without infringing Rule 5, although I guess that this is not so in the case raised here.
The base height for Unlimited competition, incidentally, is 100m.
Nick Wakefield