Gradients - complex shape - Illustrator

Hoping someone can help as this is driving me mad.

I have an initial opaque shape, which will be filled in a light grey:

I'm using a duplication of the shape to fill with gradients to lay on top. I want to create a very subtle gradient along the edge of the shape all the way round using a slightly darker grey, to create a subtle depth to the shape.

I've tried using multiple linear gradients on the same shape using the appearance panel. As follows, this is what happens which doesn't look right as the gradient doesn't follow the shape edge:

I've tried playing around with the freeform gradient tool, using both points and lines. Lines doesn't work because it only curves (a lot?!) and won't follow the outer edge of the shape. Plus the gradient would run along the line from opaque to grey which wouldn't create the subtle rounded cylindrical tube shape look I am after:

I can't see a way in which to use the 'points' option on the freeform gradient tool, as this means assigning each 'point' to the darker grey colour, but I can't see how to make the middle of the shape transparent (I'm planning on having text running along the first opaque shape that shows through the transparent middle of the duplicated gradient-filled shape):

The best work around i found that gets close t the look I am trying t achieve was to use the freeform gradient tool and the 'lines' option to draw lines around the edge of the shape assigned to the darker grey shaded colour, and to then create more 'lines' using the freeform gradient tool along the centre of the entire shape and assign the points to 0% for transparency. Here's this highlighted: And the finished effect:

I posted the same question on the Adobe forums but the answer that came back was to create a gradient along a path to use as a fill for the shape, which doesn't work because a path does not replicate the altering angles of its edge of the shape as it curves in different directions.

Was what I did the best/only way? It seems complicated and not very accurate or professional!

Thanks for reading and your patience.

Example for Luciano: