Can I ask a high-level design question?

We have BorderManager 3.8 serving our HeadOffice. We have an enterprise
FW, which BorderManager is routed through for internet access. We use BM
for access control and caching.
We have some WAN sites connected over 512KB Links to our Head Office.
These WAN sites do not have their own internet connection.

We would like to put a BM server in each WAN site, and route the WAN site
clients through these BM servers to our internet connection in the Head

Any suggestions on the best way to achieve this?

Reviewing the documentation it details some scenarios (e.g.Intranet
Network Acceleration example
I'm still unsure from this example how to configure BM and the clients