First of all why in the world did Crossroads make an outdoor kitchen sink not drain to the grey tank is stupid if you ask me. However, in my 250RB I made a modification by getting three parts. One is a 10 foot hose. Second is a Y sewer connection and third is a drain cap. This works well and I have done this on several camping trips. You follow along on this topic:
Unfortunately on the 250RB the sink drain point is lower than any point to drain to the grey tank. At least that is what my dealer told me when I asked if they could modify my outdoor sink drain to dump to the grey tank. I was willing to pay extra to have this done when I took the camper in for warranty work in June. Now I just use my other method to drain the outdoor kitchen sink to the dump.
But I will say this one more time...Crossroads dropped the ball on this issue in the 250RB.
2016 Sunset Trail Super Lite 250RB