I have a roof mounted Thule Rack & crossbars with a kayak system mounted to it. No reason why you couldn't use the same basic rack and add a ski option.
Basic Thule rack & crossbars with the mounts attached for the Hullavator:
Hullavator mount close-up attached to cross bar:
Hullavator attached to mounts:
Inside thumb mounts, 6 on each side. One is hidden by roll bar: