Not yet finished - but on it's way - finally! After having the Battery Box Covers made up for the rear Battery Boxes (long ago!) - I have finally got started on getting them fitted!
Since I had the batteries out - I started work on getting the cover installed for the single.
Then I used special Double Sided Sticky sheets, to temporarily hold the clips in place, aligning them by putting the lid on and clipping them to the closed position. After Carefully unlocking the lid, I clamped the clips in place one by one, and drilled first one hole, then bolted it and checked the cover fit - tweaking it for any alignment needs, before clamping the clip again to drill and bolt the second hole. I Did the same on both sides, then finished to tighten down the bolts.
First - were the aft most flat edges, being at 90 degrees - they were scraping the plastic trim that was not in place when they were welded up, so I had to do some trimming and fitting - for a few fit cycles to get that right.
Next - was the issue of the 4 original holes - that we first drilled in the side flanges along it's center-line, but they were along the edges of a dip, and on the side - where the hole - while vertical - would end up tipped inward on all 4 holes if I simply inserted the desired screw-nuts. So I decided to again get out the Mighty Putty - and simply use it to fill and level the space. First - I took my Wire Wheel (Actually - a synthetic replacement) in a 3" Dia. and using the Drill - I cleared away - Paint, Rust inhibitor, and underlying Rust, before using a small steam cleaner to cleanse the area of fine particles, dust, and crud. Drying that first with paper towel, and then my heat gun, I was then ready for the Might Putty!
After cutting 4 pieces of thin coat-hanger sized rod to insert in the 4 holes, I mixed the putty - one hole at a time, and then forced it into the depressed area an around the rod, wiggling the rod to keep the hole clear, and patting it down to make a basic Level condition. It was not until I got to the last hole - that I thought to use a stiff plastic Spreader - to pat it down in a true flat surface! (The others were already too hard to mold any more by that point.)
After Removing the masking and paper, I chose the size of Screw Nuts (10-24), and drilled the insert hole for them. Unfortunately - I only had handy 1/4" drill bits, and needed a bit larger. So - I took a Round file and began to work the holes to make them larger - until the screw nut just slipped in.
Unfortunately - I made one hole a touch too large, and so - after installing the screw nuts, and fitting the cover, and testing the fit with bolts - the loose one pulled up. I will have to get a fresh one - and start again - but likely use a bit of fresh Mighty Putty with the install - or some other Epoxy - and let it cure before testing the tightening again!
Here are the two covers in place - with the smaller Single Batter Box Cover forward, and the large - 4-Battery Cover Aft:
Once that test fit is in place - the next step is to secure spacers for the flanges - using 1/2" thick Pink Builders Extruded Foam, adhesives, and Epoxies, etc. to set up a hard and level offset to raise the cover flanges up so as to clear the wiring that enters the battery box from the back face.