Not sure what type you have, but I was just researching them, there is 2 main types for the D22, type that clamp using the the door seal lip and the other that you affix (probably with screws) a rail to to each sid of the roof and the roof racks then sit in this rail and can slide forwards and backwards, making them adjustable.
I dont like the idea of screwing holes through the roof as it will promote rust and leaks, unless its a quality kit and is done properly, then they are permanent.
Does yours have 2 long channels that get screwed to the roof? and the roof racks fit to them or do the roof racks get screwed straight to the roof?
If it has the rails you could always sikaflex those down instead of screwing them, it would be plenty strong enough, if they are supposed to screw straight to the roof then thats what you will have to do, I would prefer to buy the clamp on kind my self as there removable.