Very grateful for the existence of this subreddit to assist us noobs!

Looking to branch out sideways from my regular photography habit, mainly interested in shooting emission nebulae, certainly to begin with.

I'm lucky in that I have a full spectrum Canon 7D which I sent off to LifePixel a few years back to get modified for shooting IR (with external 590nm filter), so this would appear to be an ideal starting point, however, I'm also somewhat familiar with Magic Lantern firmware for canon cameras and, apparently, the dual ISO option might make my 5DIII a good option due to the lower sensor noise levels when not running the noisy stock Canon firmware (info from photons to photos dot net) 

I also have a Sony A7RIII which I recently purchased for a song in order to investigate mirrorless with adapted canon lenses among others, just to make my choices more complicated)

Still looking to try and narrow things down a bit as the number of combinations I have to play with are somewhat overwhelming - a good number of choices for the (camera) first layer, which is only compounded when you add lenses in:

• Native canon glass of note would include a 70-200mm f/2.8  mk 1 which has always wowed me with its sharpness as well as a 70-200 f/2.8 Mk III - however, zooms are not the best option for astrophotography?
• I also have a 16-35mm f/2.8 III
• and a Tokina 11-16 f/2.8 (IF) DX (for crop sensor only - won't be able to use with a Canon clip-in filter from Astronomik or Optolong?) 
• I have Canon Extenders ( 2x III and 1.4x III ) but wonder how these might affect things?

I have some other more interesting MF, adapted, prime lenses which might be interesting, especially with the 7D, which include, but are not limited to:

• Pentax Super Takumar 135 f/2.5
• Canon FL 55m f/1.2
• Nikon 50mm f/1.4D and Micro Nikkor 105mm f/2.8D (which I think I can adapt to either Canon or Sony E).

I'm lucky that my day job pays me reasonably well and allows me to finance my photography habit, so I have the option of starting by buying a decent tracker - however, I'm often guilty of diving into these things head first and then not using the stuff more than a couple of times, so I have a line on a used StarAdventurer GTI goto mount which I can always sell for about the same money if I find I don't follow through on this as a hobby. I figure that a GoTo mount will help me get on target relatively quickly for shooting nebulae?

While I would love to get some opinions on the best of the above lenses as a starting point, my more pressing question would be which filter to use.  I live in one of the (traditionally) least appropriate locations to try astrophotography, NYC, so a light pollution filter would seem essential.  I'm encouraged by the results I see with (dual) narrowband pass filters, so I think I'm likely going to choose the Astronomik CLS CCD, although I'm also considering the more expensive Optolong L-eNHance filter which Nico Carver of NebulaPhotos on YT seems to favor.

What would you think of the above options and my likely starting point of:

Full spectrum 7D <lens> GTI mount L-eNHance ?

What would you modify or suggest? Thank you in advance for any and all suggestions!