I have a sidemount plate & taillight combo, that was homemade. All you really need is a piece of sheetmetal cut to the size of your plate with a small tab coming off the side that you bend at a right angle. Pretty much like this...
Mines just thin sheetmetal that you can cut with tin snips, and painted black. Nothing super fancy, but it gets the same job done as the shinny expensive ones. Let me know and ill email you a picture, because the photopost is still down.
