The cause of the ridge is your butt. Don't believe me? Lay in your hammock and follow the ridge down to where it terminates. Since we can't do much about reducing the butt pressure try some of the previous suggestions. I tried all methods of end gather and some hybrids. The best for me,YMMV, has been Redoleary's mini bars mentioned earlier.
Most of us end up poorer here but richer for being here. Olddog, Fulltime hammocker, 365 nights a year.