Is it possible to make script with capability for certain group of users that can visit only one address, e.g. m.facebook.com? If this group write any address in browser, they will be redirect to e.g. m.facebook.com.
Maybe you could use an access rule with the web proxy which is transparently applied only for your “certain group of users” however you decide to identify them?
Proxy cant take care or SSL, so all HTTPS pages cant filter with proxy!
block 443