Is there a source for the press in trim clips? .... there are 5 per side, 3 are larger and 2 are smaller...I've looked until I have "computer screen nauseousness".
I've considered something where a flat spring steel plate could be 'snapped' into the back channel, and then just use VHB tape to hold it on. VHB tapes are used widely on modern cars to hold panels or trim.