Installing the sliding battery tray...A simple project, told in excruciating detail

I finished that last one foot of floor.
Need to make sure that the silicon at the rear edge is well clamped to Annie. Since I am parked outside the workshop, not the garage pantry, I didn't want to pull out the tomato sauce jars I used for the rest of the joists. So I grabbed a broken vise and a broken water pump for the weights.

 The floor is finished...except for all the finish work, like vinyl, tile, trim, and/or paint.

So now we can install our first interior thingee. Hint: it's not quite a utility, or a storage tank, or an appliance.
It's the sliding battery tray. Did the first picture above give it away?

The tray will hold 2 4D AGM batteries.
The tray will be mounted on a sheet of 3/4" ply with 1/4-20 bolts and t-nuts. The tray has pre-drilled mounting holes. Holes are drilled in the ply sheet as determined by the tray hole locations. The ply sheet will be mounted to the floor by screw and VHB. We're temporarily leaving the bolts in the ply sheet.

I drilled clearance holes for the bolts in the floor. You can see the four left-side ones here:

Putting down the long suffering VHB:

It was suffering from tape worms. I operated to remove them...

Using the bolts in the ply sheet and the clearance holes in the floor as a guide, I mounted the ply onto the floor.

Now it's time to get hammered.

Extend the joist location lines to the ply, and screw through the floor and  into the joists with a lot of screws.

This should squash the VHB enough to prevent any relapse of VHB tapeworm.

Pull out the bolts, and remount them, but this time with the tray.

And we're done!
The tray is opened:

And the tray is closed:

I am amazed how simply closing the tray also put my tools away.

It was a good thing that Annie wasn't parked about 10' forward from where I was working. As I was bolting in the tray, I suddenly heard a lot crash.