We use Elements at my studio. They are intended for representing live-action camera footage and we have added custom fields to store camera/lens specific settings like focal length, focus distance, shutter speed etc.
Alternatively you could use Versions, which are basically playable media and have path fields for the disk location of your frame sequence and QT movie. You could create Versions of your plates, set them as type ‘Plate’, and link them to each Shot.
We prefer using Elements as it makes it simpler for Production to manage the type and status and also keep the data for that footage all together. It’s also useful in those cases where footage is relevant to multiple shots (skies, dust plates etc). We still make Versions of the plates, we just link them to the Elements.