Hi everyone, I am having a bit of a tricky time getting a nice shape with a surface loft on a couple of my motorcycle gas tanks. I think adding more guidelines will help. I'm using the 'Curve through reference points' tool and adding sketch points to guide it on the sketch.

The issue is I'm using splines of different lengths in my sketches, so adding sketch points that are referenced to either end of the line is giving me really messy guidelines (as you can see in the picture). I wondered if there was a way to dimension based off a percentage of the length of the line, so that it was at the same location on each spline? Or is there a better way to do it?

I'm a bit of a maths dud, so apologies if this is a stupidly simple question!