I've searched, and spoken with support, and there is no prebuilt insight and no way to create a custom insight LYBUNTs or SYBUNTs to use in a custom NXT dashboard. This is a pretty standard fundraising metric and would be very useful to be able to include in custom dashboards.
My boss is actually going to want to try to do this tomorrow... So I guess it's good that I already know it doesn't work without having to do all the legwork, but this is definitely something that is used a lot, and would be helpful in the pre-built insights!