I concur with many of the comments so far. You might also like to consider the fact that if you are closer than 500ft as you fly by you might find it difficult to get a good picture as the relative movement will be quite fast.
Having said all that and noting the foregoing comments, bear in mind that you can still be within gliding distance of a deserted beach at 500 AMSL and 100 kts and convert speed to height if the donkey quits. It just depends how many risks you want to take.
I hesitated before writing the following, but I bet many people thought it anyway. If you are going to break the law, if only you and your partner in crime (on the yacht) know, then you've only got your own conscience to worry about. Many people speed down the motorway; they just hope there's not a radar gun on the next bridge. The parallels are there. Just make sure you don't buzz some bloke on a lilo on the run-in...
Don't think I'm telling you to break the law. Only you can decide that.
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"Take-off is optional, Landing is mandatory"