just a small thread shift. working out how to move a stanchion outboard a few millimeters seems to be pretty small problem in the scheme of the project. perhaps not ever putting the boat in the water with people aboard would be a satisfactory solution.
The simplified stability test is designed for monohull powerboats and addresses most of those concerns. How you predict the results before launching requires considerable infomation. Installing batteries low will help, but I'm not guessing how much, just following. But I think 8 people on such a boat sounds like a really, really bad idea. Not enough form stability, even with batteries low. Keeping a portion of the external keel would have been my thought. More likely, I would have removed the rig, installed the solar and batteries, and then decided based on waterline.