2015 Tacoma TRD, need advice

^ This. I had the same symptoms, and it was just the trailer hitch.

 

i have a 2013 DCSB and had and had the same issue and it turned out to be the front passenger side bed bolt was lose tightened up and noise went away

 

It's been said that the u-bolts are almost always notoriously loose. Even from the dealer. In fact,(I personally haven't looked it up) from what I understand the spec is said to be that the ubolts to be torqued at 37#.....yes 37. I guess it's a typo and should be 73#. The guys that more about suspension than me say that's even too low and should be 90ish.
I put a AAL on my truck....a few weeks later I was hearing an obvious clunk. I went to my buddy's house and used his impac and retightened them.......completely gone and has not returned.

Try tightening up the ubolts....