By the way, when I had an old SPORT 15, I just used a piece of SCOTCH 33 Plus black vinyl electrical tape to protect the exposed terminals of the electrical terminal block.
An alternative source might be a consumer-off-the-shelf (COTS) small plastic electronics enclosure. The HAMMOND company makes many styles of these small enclosures. See
http://www.hammondmfg.com/scpg.htmYou could drill a hole in the bottom of the box for the cables to enter from the boat inwale bulkhead. Then mount the box to the inwale bulkhead with two screws. Then the battery power wiring can exit the box via a rubber grommet on the lower face. You could also mount a toggle switch on the box to control the lighting.
You can often get HAMMOND boxes from MOUSER ELECTRONICS. Try
https://www.mouser.com/hammond-manufacturing/If you don't want to order a box, check out your local hardware store, TARGET, WALMART, and other household supply store for a suitable box.
If you can't find a good color, get a box you can paint. Use some beige applicance spray paint to match the color to the cockpit interior gel coat color.