I'm about to install the same Galaxy. Grey Ghost, your boat size / layout is pretty similar to mine, so I presume you don't think the 8-ft. galaxy is overkill? I was going to mount it just forward of bimini hardware, port side. Where do you have yours?
Never have enough Tx power, by going to the 8” antenna, the ERP (effective radiated power is doubled. Antenna is mounted about 6” to the stern, port side of windshield.
To twist the power pair of wires; stick one end into a vise and the other in a drill chuck and twist to about 1 to 1 1/2 turns per inch, remembering that the total length of the wire pair is going to shortened when twisting. Fuse at the battery and determine wire size for 3% or less voltage drop.