Usage#29b. How can I give my users guaranteed completely hands-off access to a special website?
If a special website will not tolerate even very minor tweaks to its traffic (see previous question), arrange it so that traffic never enters DansGuardian in the first place. (See question Installation#11b.) Specially intercept just that particular network traffic with IPtables, then route it either directly to the other network interface or directly to Squid without going through DansGuardian.