One of tools that is available through Segment (segment.com) is fullstory (https://www.fullstory.com/). Full story records user activities so that you can see exactly what your supporters are doing while they're on your site.
After integrating, you'll be given a dashboard from which you can view recordings of user activity.
While it's admittedly a bit creepy, we think that fullstory may be helpful to get a sense of the full user journey for your supporters. Are they having trouble finding something on the site? Are they getting stuck on one page? When people are brought to a petition from a blast email, do they sign the petition and leave or are they clicking around the site?
Another provider of this type of service is Mouseflow.