I also love the look of rear duals. I actually don’t have any cars without them at this point now that I think about it. I even put them on my Miata, even though it’s just a 4 cylinder with a single pipe, I was able to source a rear muffler section with 2 pipes, and had to cut the rear bumper for the second exhaust tip. I did that car mostly for aesthetic reasons as it’s not going to gain any noticeable power obviously. On the 4Runner, I really wanted them coming straight out the rear also, but finding a system is pretty impossible these days days since they are so old. I was fortunate enough to find the TRD dual exhaust option for mine, but the tips come out at a 45 degree angle behind each mud flap. I briefly considered just taking the truck to an exhaust shop to have elbows bent that would route the tips straight out the back, but another member pointed out that Toyota specifically designed the system that way to avoid the fumes from getting sucked into the cabin if the rear window was open while driving. That made a lot of sense, so I nixed the idea of messing with it, and over the past week, or two that I’ve had it installed, have actually grown to like the look. It also sounds amazing, especially since I also have headers. In your case, I don’t think it would be practical to route them “through” the bumper, but you could definitely run them under it on each side with no issues, other than the aforementioned fumes entering the cabin.
