Hi
I would still suggest to have a person there in site with least knowledge to handle the things if something burst out into some serious issue..
Pls backup the configs of all routers and keep a copy with u as well as in the site.
do change the configs accordingly as per the requirement and may be you can take a downtime in the offpeak hours and upload them on the routers as a startup config file.
you can do this in a phased mode not in whole or in bulk no of sites..
copy them onto the flash as a startup config file and then reload the router..
we have done this kinda config changes for remote routers/switches from central locations but i would like to agree that we did miss up one or two locations and ended up in loss of connectivity which was rectified with the service personnel over there in the site..
regds