We are using a 1 gallon shop vac and run it from the inverter
. It is small enough to stow easily and has reasonable power. We have carpet in the boat and to get the dog hair up Lynn uses a hands and knees stance she calls the rake and scrape. Using one of those thin wire bristle dog bushed, she sort of combs the carpet to loosen the hair and then vacuums it up.
I bigger, more powerful unit with brushes
would be great but there is only so much room on the boat.