What Ive done to my Patrol is I pulled out the passenger seat behind the driver
and made a platform for the Engel, No need for over priced drop down fridge slides.
Mine is a 40 ltr any bigger you may struggle with the lid fully open. I have some Engel hinges
from years ago, the boss of Two-zone posted me a set so I could hinge my engel the other way..
Ive also installed a LED light that comes on when the lid is moved, thats fused to the dead side of the power fuse
Best mod Ive even done, even made one for my ice box [Baileys]
Flat is fine ideally you want them facing the sun and then follow the sun during the day