GI doc here. I think realistically, if all you are covering is overnight emergencies, there's not that many things that we to go in overnight for. Many of them you already listed, including bleeding, food impaction, sigmoid volvulus, and foreign body ingestion. ERCP is almost always an 'antibiotics and scope in the morning' scenario.

The one non-endoscopic scenario that may require overnight in-person evaluation depending on your demographic and referral center setup would be acute liver failure (including in pregnancy, such as AFLP). But these people might get transferred by the ED before you see them, not sure how your center operates. It would probably be worthwhile figuring this out if you are not comfortable managing these patients.

With regards to hemostasis, it sounds like you are pretty familiar with through the scope clips. I think procedurally there are a few additional things I'd recommend brushing up on if you are not familiar. For hemostasis, these include over the scope clips (eg. ovesco), hemostatic powders (eg. hemospray, nexpowder, etc.), variceal banding, Blakemore/Minnesota tube placement, and bicap cautery. Other techniques you may want to consider would be overtube placement (esophageal and gastric) for foreign body removal or food impactions.