I am thinking about installing dual electric primary winches, which
are 1500 watt 12 v motors (still waiting on the electric specs to see
breaker size which will define wiring size. I believe that's startup
wattage.)

The boat has two sets of house batteries, one set on starboard about 6
feet forward of the starboard winch, one on port almost directly under
the port winch. The DC distribution panel is just aft of the starboard
batteries.Once battery set is 2 4D gels, the other is 2 8D gels.

Is there any reason why I need to wire the port winch all the way
across the boat to the distribution panel? I'm inclined to hook it up
just after the disconnect switch (or with its own disconnect switch)
directly to the port batteries. It would have a circuit breaker, of
course.