The seat clamp I think you are describing, needs to be fairly beefy or it might break.
I had one that style fail on its first ride. There is a lot of pressure on some fairly small areas. I suppose it’s possible to build a reinforced version but I don’t like the design.
Just fwiw, I’ve broken 2 seat posts in my time surprisingly (140lbs). I was never hurt or even wrecked but holy cow, it’s a looong way home without a seat.