Semi-permanent installation of 4x8 wall paneling suggestions?
Why not use a French cleat?



(link and image from Wikipedia)

One half could be glued or screwed to the back of the panel near the top, the other half screwed to the wall using toggles or other anchors. Only a few would be needed.

To add rigidity to the panels and eliminate bowing, additional plain strips could be glued horizontally to the middle and bottom of the panels.

If you are concerned about dislodging the panels or if they lean away from the wall at the bottom, you could pin them down with one or two screws at the bottom into light duty anchors (or toggles).

Removal and repair would be very quick and simple.