[Renate]

I took apart the piece of the back cover that I wasn't using.
The backbone is 1.25 mm (0.050") acrylic.
The magnet are the same thickness, that is, thinner than the ones in the case.

Mmm, I think that I'll try to split the 1/2" remnant of the back cover and remove the acrylic and the still more magnets that are there.

Edit: So I did remove that bit of backbone and magnets on the back 1/2".
It came out pretty well, I didn't even have to split the side seams.
Of course, it would have been easier to do before it was attached to the back case.

In any case, look at all the magnets that I got rid of!
So now the front flap has four magnets for the right side closure and one magnet for the Hall effect sensor. So there is no useful modification to the front flap.
Inside there are the four remaining magnets as shown in the previous post.