For extended stays we use a garden hose cap and run just a small hose from the cap to the sewer. That way we can bleed off grey water as needed. On my rig the grey fills up in a few days if we are using the shower and washing dishes. The black can go a solid week. By leaving the grey closed except for bleeding off the excess I always have plenty for flushing the hose when I get ready to empty the black.
Another option to consider is a macerator/pump system, then you only need a 3/4" hose and they aren't as much of a tripping hazard as the stinky slinky.