Given the Cheapy-ERF is ready, it's time to explore its opportunities on white light imaging. Herschel Wedge cannot be used on compound telescope usually, but if there's a ERF on the aperture end, I believe it's use-able.
Without anything on the aperture end, sun light kill burn the OTA of a compound scope, or at least deterioate the coating on the secondary, etc. After using the Cheapy-ERF, sun light will not burn the OTA and it will thus be safe.
The transmission through-put of Cheapy-ERF lies between a Polariser filter and a ND3, so I suppose if a Cheapy-ERF is used at the front, maybe we just don't need to Polariser any more.
Experiment will tell.
The image quality, however, will be limited by the Cheapy-ERF. But at least, the setup will be more durable than a Baader film.