Thanks to all who like this build!
The bottoms of the pylons are reinforced at the whole length with a strip of 0,3x5mm glas-fibre. To be able to add several "cargo pods" each pylon got two 0,1x10x10 steel plates folded around the glas-fibre strips.
The "heavy" magnets are mounted onto the top of the cargo - the main advantage is, if the plane comes out too heavy the magnets stay on the ground
. I used the same principle at my SU-22
A pic to explain how the pylons are build and a 2nd pic of a possible cargo-configuration: