Something like that should be fine. One thing to recognize is that some types of flow totalizers do not record flow very well when the flowrate is low. The nutating disc flow totalizer style like you have pointed out above, DOES work well at both high and low flowrates. That is a reason why most water utilities use them to meter home accounts. I don't have a recommendation for a manufacturer or seller, but I noticed this site: flows.com/totalizer/