I have them mounted on my 07 Tacoma using the L2S Sport Rack Brackets on my Toyota bed cleats. They work great! Very strong & secure. I have my kayak, bike, & surfboards all on board with plenty of room for my gear below. Never had a problem!
You could also try the L2S Sport Rack Bracket that adapt Thule & Yakima accessories. It's less expensive & a little more functional in my opinion. It fits directly onto the Toyota rail system & probably fits the Nissan as well.