Roll up Tonneau with backrack and over rail toolbox help

[MO GMC]

Hi everyone. I am looking to install the access tonneau cover,backrack and a weathergaurd low profile toolbox on my 2016 gmc crew cab.

 

Someone was telling me that you can't install all three items, even though access sells the short cover version for a toolbox.

 

Anyone know if this is true? I would like to have all three items.