Unfortunately, Yakima tells us that their LockNLoad platform isn't intended for use with a cargo box, as there is no safe way to attach the box to the platform. Your best bet would be to attach the box directly to the vehicle's crossbars. www.etrailer.com/Roof-Rack/Yakima/Y05044.html
If the # Y05039 clamp adapters are used, they'll fit crossbars up to 2-3/4 inches wide. I believe the Thule AeroBlade crossbars were wider than that, but it's been several years since those have been available, so you'll need to measure the width of your crossbars to make sure they'll fit. www.etrailer.com/Accessories-and-Parts/Yakima/Y05039.html
I trust her
Can a roof box be mounted on the platform?
Unfortunately, Yakima tells us that their LockNLoad platform isn't intended for use with a cargo box, as there is no safe way to attach the box to the platform. Your best bet would be to attach the box directly to the vehicle's crossbars.
www.etrailer.com/Roof-Rack/Yakima/Y05044.html
Does this Yakima LockNLoad fit my 2016 Nissan Frontier I got a Thule Traverse Aeroblade bar set up on my truck
If the # Y05039 clamp adapters are used, they'll fit crossbars up to 2-3/4 inches wide. I believe the Thule AeroBlade crossbars were wider than that, but it's been several years since those have been available, so you'll need to measure the width of your crossbars to make sure they'll fit.
www.etrailer.com/Accessories-and-Parts/Yakima/Y05039.html