Sweet van! Seriously, making it look odd may work against any plans about stealth camping you may have. Close to stock may be your friend, IOW. And save more money that way.
If you're getting near 16 on the highway then it's doing quite well. What does it weigh and how have you outfitted the interior? (If it isn't prying).
A great choice for a camp van. You might look up
Cummins 4BT & Diesel Conversions Forums
for info on an engine that, with manual, would put you right on up there for mpg.