I've had 2 whitewater kayaks (30 odd lbs each) up on it and noticed no deformation to the top. even turned hose on with the spray nozzel, no infiltration of water. the mounts actually were from a blazer that i had oh 7 or so years ago. still had the mounts laying around. I don't remember what the suggested load was for them, sorry.

 

Hey they stole my idea!!!
Zut alors!


I will have to take that as a compliment (great minds think alike).