How can I handle a huge amount of logging generated from frequent table rebuilds?
one option (if feasible for you considering the downside) would be to change the database to bulk logging and bcp into the target table from a view reading the source tables.  the actual logging should be minimized, but the log backup will still be huge as it will include the changed extents.  a downside of bulk logging is that is compromises the ability to point in time recover to a time frame during the bulk logging operation.  make sure you take a log backup immediately after the bulk import