I like Theo's thoughts. but would just add that an elevated area larger than the largest fish you anticipate cleaning should be in place next to the sink. I built a shelf just about waist level and on it placed a large cedar block which is perfect for fish cleaning.
Regarding what to do with left-overs from fish cleaning....if you have a garden, use them there. The first occupants of this country used fish as their garden fertilizers...it works just as well today as it did when they were here. It works!!
