The main question is - how far out of date are the machines on the remote site? I'm guessing that they are a long way out - possibly they're new installations of VSE - and so they're trying to pull the full 100MB+ DAT package...
We publish the DATs as a combination of incremental files, and the full package. If a client machine is less than 35 days out of date, it will try to download and use the incrementals: otherwise it will ask for the full package. Assuming the machines are up to date, then each day they will each only require one incremental which averages out at around 200kb.
In the environment you describe putting a repository on the remote sites would not be a good idea - the daily replication load is around 130MB. You could use a lazy caching superagent but with only 2-3 machines it's a bit like overkill. My recommendation would be to get the remote machines up to date manually by (for example) running a superdat on them: from then on they should be able to update over the wan using just the incrementals.