Leo I Galaxy

Well, I don't know, I'm not really keen on sacrificing the aperture.

Well, it's not a significant sacrifice at all—just one-tenth. You just need to cover the clips that hold the primary mirror.

Against an unevenly lit background, will this help? Or is it due to light pollution and can be solved with filters like dual-band?

I'm not entirely sure what you're referring to. As I noticed, some of your photos have "dark spots" in the center of the frame. This is due to incorrect background alignment in Graxpert or any other similar program. FLAT frames could also improve the background. If you could share the unprocessed stack, I could take a look at what the issue might be.

You can try, where should I send it?

You can reach me on Telegram - https://t.me/masfett