Non-pro here.

The issue with an 'everyday' camera in a different system is that those reactions burned into my spinal cord are typically wrong.

My solution, an old D600 with 20mm f/2.8 D or 50mm f/1.4. With either lens, it's a bit over a kg (1100g-ish) with L plate mounted (because I always have some kind of tripod in the car). Drops right into a LowPro trailrunner belt pack. Trade in value on that camera and lenses is low enough that I won't be super upset if something bad happens.

Same external UI I'm used to. Same control wheels, same BBF, same AE-lock, same stop-down button. 24MP and well over 13EV DR means I have a lot available in post.