I want to mount a roof top tent on our 100 using part of the factory rack. I'm comfortable in fabbing up something structural to mount it to and distribute the weight. But I'm not sure how much weight can the 6 factory post handle? The tents weight is around 120#, 25# +/- for the additional steel and another 400#-500# in people,dogs, and gear. Some of the weight will bare on the ladder that supports the one side once the tent is opened up. I'm not sure how much weight or how to figure it. Any thoughts or experience?