I did not intend to snap the picture in the post above. I was taking pictures of my grandkids (crew) in the bow while I was driving and inadvertently snapped a picture of the area in front of the passenger seat.
The gray surface in the lower left and right corners is the boat's deck. The sealed hatch you see in the lower left of the picture is the hatch over the fuel tank. The off white structure in the middle with the fire extinguisher on the right and the glove box on top is the passenger's console. The four screws fasten the console to the deck and the sloped area forward of those screws is the footrest for the passenger. The dark panel that I have circled in red is the hatch with a clasp on the right. There is an identical hatch and compartment in the helm's console.
I can mount the batteries directly to the deck surface beneath the helm in this compartment.
Easy Pesy!
Thanks Again for the guidance, Slow