Skybolt Seat Height and Stiffening around Cockpit cut-out in Aluminium Sheet

[Jan]

I am looking for guidance on seat height in my open cockpit Skybolt. Am using Steen Aerolab's bubble windscreens. If I draw a line from top of windscreen parallel to top longeron, where in relation to this line should the top of a head be in front and rear cockpits? In rear cockpit maybe top of head should be determined by setting it just below top of rear turtledeck?
I would also appreciate help in making edge of cockpit cut-outs sufficiently stiff so that not-so-young pilots and passengers can grip it with their hands to enter and exit.
Many thanks, Jan

 

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[Jan]

 

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[Jan]