Since your mom doesn't have the raised factory side rails on her 2006 Nissan Xtrail, it must have the flush mounted rails. The Thule AeroBlade Edge Roof Rack # TH7602-TH7602 and Fit Kit # THKIT3063 which will bolt into the factory locations hidden in the flush mounted rails. I've attached the installation details to assist. I then recommend the Thule SUP Taxi XT Stand-Up Paddleboard Carrier - Roof Mount - 2 Boards # TH810001 and have attached a video to assist.
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