Kiwi Equipment also offers this grille which also serves as a grill...
They say the "Kiwi-Kühlergrill macht seinem Namen alle Ehre" - The "grille" lives up to its name (their pun intended). Installations involves "wird einfach gegen den Originalgrill ausgetauscht" - its simply exchanged for the original grille and "mit Befestigungsschrauben" - and comes with mounting screws.
I assume it doesn't come with the rocks to set it on, hopefully those can be found wherever you need to cook in the wild.
Not sure I'd want to put it back on the vehicle after cooking on it, the grill in my backyard always has meat drippings and other debris on it after barbequing. I was going to draw a Jeep concept version of this but decided nobody would ever want one on their Jeep so I decided not to. And I don't think I'll be developing a Jeep version of this
.