Subaru has a procedure for replacing the rear body panel. Per our contact at Subaru, the 2015 XV Crosstrek repair manual is the same as the 2014 XV Crosstrek manual. The procedures can be found at

Note: Subaru refers to the rear body panel as a rear skirt.

For short videos that show how to purchase and access the Subaru collision repair information, check out the Subaru OEM Information page.