we are also in the PNW and on a 30' live aboard, but there are only 2 of us... we use the Soleusair 30 pt model ($180 through home depot online) and it sits under the dining table to the back of the seating. Yes, it is a little large.. you might have trouble seating all 4 of you at the same time while it is there... and we only run it at night since during the day the entryway is usually open so would be a waste to try and dehumidify the entire outdoors... it pulls 1-3 quarts of water out of the air each night for us.. manual says it uses 420 watts 3.8 amps.
be advised, you don't want this sitting right next to someone trying to sleep, it alternates pushing out warmish to cool air out the top depending if it is dehumidifying or running the fan waiting to pull more water out of the air. Will drive you nuts trying to decide if you are freezing in your sleep or baking
the only place that seems to not stay 100% dry during the night this way is the extreme front end of the V berth where blankets bunch up at our feet... but it is not bad. If you stayed buttoned up more and ran the dehumidifier longer each day it may not be an issue.