Mega Menu with images

Hi there,

after having tested several Mega Menu Plugins and played around with the mega menu css in GP´s Documentation and a lot of ideas from the support forum, I am still not happy with my results of creating a mega menu like this: https://www.boeing.com/

Basically it is a very easy grid format: 4 columns, each column divided to image+link column.
In my case the child items come first as a second level and I´s like to add a few blog post items (selected manually) as grandchild elements

Give me a hint on an approach.

I thought different ways with GP´s Mega Menu-instruction
1) Add the image before the child item and before the grandchild item -sounds simple, I just miss ho to do that :)
2) The Mega Menu affects only ONE submenu, so what about creating a hook element where I have 100% control of the design, and hook it under the menu if that is hovered/clicked - what about this idea? Doable in any ways?

Let´s see what you think.

Erika