We have owned a 2106 DS for 2 years and the small grey water tank is one of my few complaints about the trailer. Even practicing conservation, the best my wife and I can accomplish is 3 days before the tank is full. Some of the things we do are collect dish water in a pan and dump it into the back tank, take Navy showers, and use the outside shower to heat up the water in the inside show before turning it on.
I have looked at installing a composting toilet so that we can tie the grey and black tanks together but after viewing some videos on the reality of using a composting toilet have decided that it is not a good solution for us.
I have also looked into the various methods for transferring liquids from grey to black water tanks but have not been willing to take the plunge on any of them.
In the end, we have gotten a 25 gallon tote and use it to empty the grey water tank every 2-3 days. This means we need to be aware of the campground layout relative to the location of the dump station. We camped at one state park in Florida where the dump station was literally 5 miles away from our site, and even though we can pull the tote with the truck, 5 miles is a bit much to haul a plastic wheeled tote.