That's actually good for me to hear (not so good for you). I'm getting 13.8L/100km with a 2 inch lift, roof top tent, bull bar, winch, 245/75-16 BFG KM2 tyres and loaded to 200kg short of GMV.
I have 2 different tunes from TD5inside and original and a second one that Jose did for me because my fuel economy was pretty bad with the first tune.
Before I started modding I got 10.5L/100km with a box trailer on. I was running the 18 inch wheels, the trailer was full of 5 x 16 inch rims with the roof of tent in it's box on top of the trailer and an awening too.
I really didn't expect fuel usage to go up that much since it did so well while towing the trainer.
Happy Days.

