Just come across this thread, how did the system work out?
Just to add my 0.02 USD worth, I'm using a Manfrotto 724B (Modified).
I have filled the bottom section of the legs with about 2kg of lead shot mixed with glue. Makes it nice and stable with low weight.
The upper sections have medium sized holes drilled to allow water/air to flow and aid drying post dive.
I have also replaced the bottom feet with eye bolts, the theory (un-tested) is that I can then use it at extreme angles or even upside down on and in wrecks by carefully using bungee cord.
To attach it to the housing I modified a large stainless steel bolt head on a lathe and then drilled though the housing. The Manfrotto quick release plate is then fitted on the under side of the housing. (Ikelite housing).
As for photographic results sorry still work in progress, as my teacher used to say "must try harder".
Do you have any pics of the legs with the eye bolts in place?
I too have a Ikelite housing and I was thinking of a quick release plate like you have.