I used an 1/8" steel rod inside the Coroplast channel to for the slight bow need to clear the wheel. Tabs with threaded holes would be the way to avoid the tape that I have been living with for years... They need to come off when the wheels get rotated, etc.
Neil are your front and rear wheel skirts both just taped on? I might cut some front wheel covers this week and tape them on before I leave on my highway trip this weekend. Proper mounts will have to wait a while.