For my workshop I bought an IR heater. The holders available here did not make a trustworthy impression, so I decided to construct my own holders.
My holders are actually only spacer sleeves, they do not have to take any load. The panel is supported by long (110 mm) screws.

IR Panel:
KESSER® Infrarotheizung 425 Watt
https://amzn.to/3GRiTy1

Fitting screws:
Spanplattenschrauben A2 Senkkopf Torx 6X110/65
https://www.screwsandmore.de/de/sortiment/schrauben-und-bolzen/holzschrauben/spanplattenschrauben/senkkopf/torx/teilgewinde/6mm/4410/10-stueck-spanplattenschrauben-a2-senkkopf-torx-6x110/65?c=19770