chanrobi

Could be a good reason to do some bicep curls at the gym

Canons don't do well at low iso, for that camera 800-1600 is better for IQ

Astro modded camera is not 100% necessary, gotta get away from that thinking Go buy a used EOS M for $100 USD and install Magic Lantern and go for it. https://clarkvision.com/galleries/gallery.astrophoto-1/ Look at these done without a modded camera.

There are many options for battery packs like that, that was just one example of a company providing it. If you look at the form factor, they are essentially a car battery with a engineered for you interface to plug in various things, it's up to you to find the battery within the budget and the # of ports and power you need

You need a lot more total integration time especially at f5.6

You'll need one of these https://www.jackery.com/pages/portable-power-stations For DSLR, you can use multiple batteries, but you an also get a dummy battery with a usb plug. My current setup does not have as much power needs as yours, so I just run everything off a 30k mah, usb battery bank with the appropriate outputs. A battery like the linked should have a dedicated port for each thing you're running. Don't think splitting them is a good idea