You want to make sure it is "aircraft" type/safe paint stripper. Better for aluminum. Since you sprayed it on. I would say mix it in a bottle and spray the fins after they are warm (hair drier at most ??). then lay some towels on top and heavily soak them in the solution, patting them down as you go. Make a form of the front with the completely soaked towels and let it sit. Prolly best to then flip it after it sits onto an easily cleanable surface and use an air hose to blow back towards the front. Queue elbow grease .