Here's one that should be easier to do: using the current map as the battlefield.
Basically, take a screenshot of the map and use it as the battlefield. Use the map passage settings to determine whether a character can move to a certain tile or not. Then we can simulate on-map battles, even though it's a separate battle scene. Ideally you would have your battle sprites and map sprites be the same so that it's a smooth transition.
Not only can we use the map as the background, we can potentially load in events as well. Maybe there's some boulders on the ground, you would load that into the battlefield.
Perhaps you can destroy the boulders in battle and it would be reflected on the map?