I think it would be fine, none of the vehicles have weight limits on their roofs into the hundreds of pounds. I think the crossbars are rated for dynamic weight, taking into consideration momentum, braking and whatnot. Plus, I would say the crossrails posted rating is probably half of what it really is for safety ratings, the company my father owns builds trailer couplers, and they always rate them at half or less of the actual fail point to prevent lawsuits and liability.
I predict future happiness for Americans if they can prevent the government from wasting the labors of the people under the pretense of taking care of them.
Thomas Jefferson