Hell everyone - I think the multi-board mirroring would be a good fit for this. With that you could easily connect an unlimited number of board up into a single “overview” board which displays all of your totals (along with other fields you wish to summarize).
Consider it like the footer on each board contained within a single item/pulse on an overview board. This is an example overview board I built in my test environment using the multi-mirrored boards:
There is a separate thread on the community discussing this:
@AronK has been awesome on getting this BETA feature added to accounts.
Hope this helps,
Mark