I'll be installing the RK Sport fender flares shortly here. I currently have the Rokblokz XL mud flaps, but they aren't going to work with the flares since they attach to some of the OEM clip locations in the fender wells. Guessing I will have to get creative and attach the flaps to the flares if I end up wanting to use both.
The New Zealand spec Ranger RTR appears to have both the RTR flares and front+rear mudflaps, as seen on the white press truck. I'm curious about this setup as I have RTR flares on my truck.