The 'outlook' for the Saturn Outlook is not that good for using your current Thule kayak stacker and load bars. Thule Racks currently has no fits at all for the 2008 Saturn Outlook and it looks like they will not be releasing any new compatible products anytime soon.
So your only option is from Yakima Racks, providing you have the 2008 Saturn Outlook with the factory rack cross bars included, not just the side rails. Yakima Racks does make the Yakima LowRider MAX base rack system for mounting to the Saturn Outlook siderails however the bars will be much too close together for carrying kayaks. This is due to the strange side rail design of the Outlook, which only provides a small opening in the middle to attach the LowRider Towers. This will give you only 20" of spread between the Yakima LowRider MAX front and rear crossbars. Not even close to the required 30 inches of spread for kayaks.
If you do have the 2008 Saturn Outlook factory roof rack crossbars installed, then your best bet is to forget the Thule kayak rack items you have and purchase the
Yakima BigStack kayak stacker. The Yakima BigStack mounts directly to the Outlook crossbars allowing you to carry all your kayaks. You'll want to be sure to adjust the factory crossbars so they are 30 inches apart as well. This will ensure a safe platform for your kayaks to travel on.