After getting great help and suggestions from other builders on the Sonextalk discussion group (some included pictures), I became convinced that I did not have to mount the box to the firewall with removable hinge pins. It seems the Jabiru folks have a large cross member at the top of the engine mount that precludes removing the battery from the top; it's open on the AeroVee that I'm building.
I also did not have any sufficient quantity of .032 sheet stock remaining. Kerry at Sonex said that I could use .025, of which I have plenty.
So, tonight I checked to see what other pieces would be required to be cut from my remaining 3x4' sheet of .025, and I'm glad I did. The two gear leg fairings (each 10x25"), and the tail cone fairings (each 6x16") also have to be made. Played around with layout arrangements on the sheet, then cut out suitable material for the battery box.
Marked out the bend lines on the stock, and drilled 1/8" holes at each of the bend corners as per plans to provide stress relief. Cut notches for the upper lip, which is bent over for both strength and neat workmanship.
Marked rivet hole locations; still have to drill these.
