I have never had a low level endo. but would assume the letter of the law says you can go 0ft if so possible. HOWEVER I also would say that without having to look the rules up that there would be a clause saying 'as low as required without jeopordising the saftey of the aircraft or property.
As a licence holder you would be expected to use your judgement as a fit and proper person so determine wheather or not you are too low. If you hit something you will prove your judgement is not that of a fit and proper person and risk your licence as a result, even at 499ft and above.
In NZ there is no endo for low flying you just need 'reasonable cause' to do so......... ie SAR, top dressings, surveying etc. That said I dont think a judge would buy your 'just cause' for buzzing your mates on the beach and again you will be hung out accordingly.