Here is at least one example of EP projection:
https://www.cloudynights.com/topic/7...io-2021-09-10/
I'm no expert in planetary imaging but I suspect that using a 4x barlow may prove very difficult! I noticed for example that a user of a C14 Edge uses a 2.5 barlow and achieved terrific results. The larger aperture would support this resolution and short exposures due to the greater light gathering ability. At 5,000mm FL on your scope I suspect you would need longer exposures (less lucky seeing!) and rather perfect seeing. I was able to take some satisfactory images with my TEC140 and 2-3X barlows but these couldn't compete with large aperture mirrored OTAs.
Peter