I'd seen advice on removing arch liners rather than removing the wheels and drilling in situ but not pictures, please see attached.
Take one side off then tape flap to the other side to find best location. Do first side (test fit if you want), then repeat on the other. So much easier to guesstimate when they're next to each other imo.
1 big attachment at the top, 3 at the bottom, a twisty one inside and a small fiddly one on the outer arch.
To remove the clips, from the arch, free the top or bottom and work your way down. It's much easier ln the second side.