Our our CCV Medium Top we installed the Thule/Yakima low profile tracks. They are through bolted into the interior (see the last picture, the black circles towards he outer edges of the top are the interior fasteners.
Due to the taper of the roof front to back, they were installed in two parallel sets, the front set a bit narrower than the rear set. You can this in the picture with the solar panel. The tracks up front hold the attachment brackets for the solar panel, the rear set of tracks hold the attachments for the Mega Warrior basket. The basket attaches directly to the the tracks to keep the profile as low as possible.
For holding skis, I run a set of ski racks across the top basket. I could also remove the basket and mount feet and cross bars on the tracks for more flexibility.
The top is plenty strong. I have stood up there many times loading the basket or cleaning the solar panel. the restrictions come when lifting
. The geometry of the medium limits lifting capacity. Carrying/Load capacity has never been an issue for us.