FunPhantom

Hi everybody. Long time lurker, First time poster here. I bought a bakflip cover and bakbox a few weeks ago and realized the bakbox was not quite as large as I would have liked and i am looking for more storage, and would like one or two of the longer over the wheel well type of boxes. the problem is I'm not sure which ones will fit in my truck and under the bakflip and the bakflip rails. I'm looking for something larger and longer than the "swing out" type boxes.

Anyone have any suggestions?

truck info: 2013 FX4 Super crew 6.5'bed 5.0 engine, bakflip f1 and bakbox.