OK, looking a bit rough around the edges but if it successfully holds a battery and a regulator/rectifier while supporting a mount point for the airbox, I call it good enough. Used 4 6mm blind "Tee" nuts for attachment.
All this epoxy and glass fiber goop is making me wish I knew a thing or two about TIG welding aluminum...heck, pop-riveting and using a sheet metal brake would be fine enough for this application!
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Detail of how the airbox tab attaches to the tray...
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Here's how it looks installed...that air filter is a wee bit too long there...