I bought a set of universal crossbar mounting brackets to retrofit my old snowoard racks to my factory rack and they work great. Not sure of weight capacity but they may be an option that would work. etrailer.com LockRack Watersport Carrier Universal Crossbar Adapters
Make sure the truck is completely off before unplugging and removing doors. Pretty sure it will always look for the door if it is removed when power is on
I know there was a thread on this in the past cant remember what the solution was. Cant remember if they did something magnetic or just went with the velcro. My search did not turn anything up but I know its definitely in the =forum somewhere.