Great question. You're going to need an RTT that sits quite high up off of the rack to fit both, from the looks of it.
I am sold on a fly rod holder like the one you have. I just went on a 2 week fly fishing trip and it would've been great to be able to keep the rods together while traveling between spots! Our RTT sits on a trailer, so how the holder sits on a rack isn't an issue.
I have a RTT and the 2banger River Quiver. I tried every which way to make it work with my awning AND RTT, but alas, it doesn't.
Before I had the RTT it worked perfectly.