Displaying Averages for Stacked Bar Graph

I'm currently trying to show an average line to a stacked bar graph. I was thinking something along the lines of this:

My problem is that I want to show an average for a stacked bar graph, similar to the one shown:

My idea was to have another bar that just has the averages of each of those stacks on the top, and the lines at the end of those bar goes down so that they are a good reference for each of those metrics. The obvious problem with that is that the bars don't line up so the lines would not be too meaningful except for the first one since it's the only one guaranteed to be aligned to the left. It is important that there is a metric to show total length, which is why I'm so stubborn with using something like a stacked bar graph and not just separating the bars into 3 separate lines, but I'm open to any ideas that are not stacked bar graphs (as long as they still show the total length).

I haven't found any sort of discussion like this online which is why I'm posting here. I'm just looking for ideas on ways to visualize this. Thanks in advance for any contributions!

If it helps, for my sake, there would only be three bars stacked on each other.