I did the same except that I put a metal washer between frame and seat post. And it works really well. I did the first ride today on the modified seat - and it felt very good.Have raised my seat by shimming under seat itself and then put a nylon washer between frame and seat post on the forward seat bolt. Feels (for me ) far more comfortable.
Be interesting to see the drawing.One that provides some slight spring action to help the seat absorb some of the bumps in the road.
He's thinking about a design (drawing to come) where the seat bracket has a heavy spring hinge
behind the 2 side bolts and just before where it connects to the seat.