Topband: Vertical Antenna on a cliff above the Sea

[Robb Webb Proprietor of Robb Webb Photography]

Good day fellow Topband Experimenters. 
When it comes to antennas I am a keen experimenter but technically a suck it and see merchant rather than a design pro so I ask for your expert opinions. 
I live near a high cliff overlooking the sea. The cliff faces south, is a good 100ft high and is made up of mud and clay that over the years has been collapsing into the sea. I am considering mounting my Topband dipole as a vertical antenna above the cliff edge with the ground portion of the antenna going down the cliff edge below the vertical portion. I'm aware I may need to add radials but is there anything else I should need to consider. This is in preparation for the Boxing Day Stew Perry contest. 
Thanks for your help. 
Robb 
G0URR 


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