How to create a complex shadow in Illustrator?

Question

Graphic arts

The question has two parts. It is worth clarifying that shadows must be legal for vector stocks, i.e. no raster.
=== 1 ===
There are enough methods for creating shadows in Illustrator, most of them were well painted
by Yaroslav Lazunov on the vectorboom website . One thing - they are all based on paths.
I'm looking for the "brush method". I suppose in theory it works like this:
1 - an ellipse is created with a radial gradient from white to black in the multiply blending mode
2 - the ellipse is converted into a mesh, we simplify it in lowpoly
3 - the brush is set up with this mesh attached to the brush
4 - we smear with the stylus, we get a set meshes Is
it possible to implement in practice? Is there an easier solution?
=== 2 ===
I have already created a shadow according to the stroke principle and subsequent conversion to a mesh. How it's done, read here
Part of the shadow is drawn by me, but I'm already tired of continuing to build paths. There were small scattered objects. What is the best way to give them shade?
I would like to achieve such a result. Perhaps there is the same brush from the first question :)

Answer 1

I had an idea, but again from theory)
What if we take the top of this very card, move it to the very bottom under the layers and blend it?