Thanks to all who replied;I can look into this a little further now as I was afraid it would be out of the question.
Rene,you brought up a point with lift though, that I hadnt considered,so will be interested to check that out more.
Mauri buoy-you have a very solid looking set up there.Was it custom made for you or available from a supplier?
jwalker -the larger size of yours would I have thought exagerated any lift issues,so if you have had no problems then maybe it would work for me.
Seems from the photo yours is supported at the back as well as the front.(Hadnt thought of that approach, but probably safer for the larger tops)
I had toyed with the idea of making a t top framework with almost a "roller shade "type canvas that could be deployed once anchored.That way I could eat my snack and fish in comfort!
Will get out the drawing board and put some sketches down on paper.
Have to do something while waiting for my new boat!