Husky Rear Wheel Well Plastic Liners 2024 2500 HD

[BCGM]

I finally got around to getting the above Rear Wheel Well Liners as out 2024 2500 HD Custom did not come with rear wheel liners 

Included with the liners there are some plastic Christmas tree fasteners with washers .

I can see that these  will work in the round holes in the sheet metal  of the wheel wells but what about the line of small square holes  in the sheet just above the frame ?

Did you use the round Christmas tree fasteners in those holes as well ? 

Also where do the washers get placed that came with the Christmas tree fasteners ? On the back side of the sheet metal to hold the fastener ?

Thank you