I have had hood stack, rear single stack, have had it dumped right under the passenger seat, dumped in front of back wheel on all my different past trucks. most of those were stoopid loud . I can say my EGT cool down time was like 20 sec tho. ha.
so I wont dump it right after it crest the axle. it will be closer to spare tire area. I have used AEROTURBINE mufflers in last 3 trucks. those really removed any sharp harmonics and freeway drone. I don't know what the delete pipe will sound like on this long bed truck but if it has a drone I will put up something. one of my past trucks during summer and drags there was just a straight pipe, winter time when the truck got dumbed down and used some in town, I had a very long Donaldson Muffler it was 51" long and and maybe 9-10" diameter for a 5" pipe,
was a straight thru design with minimal perf and no packing. that was a beast and better than the expensive diamond eye etc that were getting popular. A person can get a nelson or Donaldson from tractor , big rig and farm stores for pretty cheap. I know it was like 2008 or 2009 but i bought it for 50ish $.