Upgraded to LP Aero Plastic (SG) solar grey bubble acrylic doors($460 each). Used keyless rivnuts with Loctite and screws. Must use acrylic drill bit.
Removed cross brace.
I did purchase the window install kit($125), but did not use the through bolts provided(over 100 was provided). Used the old door as a template and fabrication was fairly quick. Used 4 1/2" cut-off wheel to trim windows. Its much faster than a dremel tool.
Views are spectacular and adds 3" of cabin width on each side, for a total of 6".