Not sure about service dogs but have some knowledge regarding ADA, accomodations, and long shifts in M3 and M4. Some folks have it in their letter of accommodation (LOA) that they need a 12-hour break in between shifts. I've also seen folks who have break times incorporated in their LOA, for example, 30 minutes of break after 6 hours of work. Usually, because of the ADA and your university's disability office guiding this, clerkship directors and admin are pretty understanding of it. And, since the disability office guides this, they have a list of reasonable accommodations or might reach out to other colleagues to navigate it.
Now realistically, it might affect perception and grades on a day-to-day level. Obviously not fair, and ableism exists in all fields including medicine. But, just being honest. A lot also depends on team dynamics. And, the onus still falls on the student to have to ask to leave if the day is running super long. You will need to get very comfortable saying "I need X, because of my accommodations" because teams change frequently. I have some invisible chronic conditions, and I often find it hard to ask for things that I am technically granted in my LOA. Also, for example, certain fields like surgery were pretty easily out of question for me due to the physical demands.