My plan is two sockets at the lower front and rear and a cam-lock at the center top.
The skirts will have a vertical 3/4" tab and the fender will have a section of 3/4" tube with a single slot at 45°. The skirt is offered up at an angle and the tabs are trapped between the top and bottom of the tubes when it is rotated into position.
The cam lock might be from a old Type II gas flap door; then I could use an OG church-key.
If your skirt overlaps the fender, maybe put a fin inside that follows the front lip of the wheelwell so it blocks the air if it does bow out?