I don't know how burly the OEM rack bars are. I know that Buddy and I did a test fit of the larger of the two tents on my LR3, and we used Yakima load bars and feet. The large tent is actually quite huge, and though doable, I was uncomfortable with it's size as I was intended to go through Nightmare Gulch which has some narrow overhanging bits that I did not want to hit with a loaner tent
Buddy uses the same Yakima bars on his Classic, and with 4 people in it, plus the weight of the tent (which is about 100 lbs for the big one), it was plenty strong. Are the OEM bars that strong?
The actual attachment of a tent to a rack or load bars is quite uncomplicated, it's just u-bolts. Or maybe you could use
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