Whoooo Boy! I'm glad you're working on this!
I also have a Tepui RTT, which I've bolted to a work rack on a 4wd 'Yota.
I love the thing for our off-road adventures, but it's such an aerodynamic disaster, I've been afraid to post anything about it.
The way our RTT was bolted to the work rack, there was a 6" gap between the cab and the tent. This diverted a HUGE amount of wind down into the bed, making our dogs miserable.
I was working on a thick canvas cover to run completely over the tent, from the front to the back of the work rack. Unfortunately that project's on hold while I build a new diesel motor for it. (long off-topic story...)