OK Surfacing Guru's, I have another question for you all!

When planning out your surface models, how do you make sure you won't see visible creases/flat spots/distortions if you are planning to mirror?

I've seen some people struggle with this so much that they refuse to mirror all together. And I'll admit, sometimes it is hard for me to match the smoothness of a continuous spline vs mirrored halves when wanting to model a truly organic form.

Here is what I mean, this is a mistake I used to make (and that I see commonly with beginners) - setting up guide curves and making my splines C2 continuous to the (flat) reference surfaces. This would inevitable result in gross flat spots when mirroring and a visual discontinuity

The "proper" way I've found is to set the profile curves to C1 tangent, and manually adjust them so that there is some curvature at the interface. Having to imagine how much curvature you want at the mirror boundary. I try to make sure that the rate of change of curvature is nearly flat near the mirror boundary to prevent any visible seam.

I'm happy with these results! But... it's a lot of pushing and pulling and tweaking. Is there a way to parameterize this that I'm missing? An easy way to "set" the amount of curvature (specifically for a style spline?)

Attached file in 17 format if anyone wants to play around