There is a hack some of our Tacoma customers with only 44"  between the wheel wells have used to fit in a Rev Pick-Up Truck Tent.
Use a box knife to cut the wheel well shape in to the hard foam at the bottom of the mattress.  It takes about 5 minutes and doesn't alter the performance of the tent.  Then you can squeeze the tent in between the wheel wells, and you won't even notice once inside the tent.