Get you 2 of these one for positive and one for ground, rig a jumper from the power to the one beside it then you ha 2 hot and ground screws on the other side. I would rerun from battery with 10 gauge twisted pair 16 would be to light on that run for 2 finders in my opinion.
Blue Sea Systems, Terminal Block 20 Amp
Or you could go this route
Sea-Dog, Combination Buss Bars
Also I would run 10 amp fuse at battery and you recommended fuse at finder wire end hooked to terminal block.
Proud Member of Team Geezer
Charlie Weaver USN/ENC 1965-1979