If the database is only used for read only and from the information you have supplied my personal approach would be the following.
Have the option 'Truncate log on checkpoint' and 'select into/bulkcopy' options are set on the database.
Instead of using the DELETE statement use TRUNCATE TABLE instead. This will not use the transaction log to log the records deleted.
On your BULK INSERT statement also use the TABLOCK hint option. This will not use the transaction log to log the records inserted.
This method will get your database operational in the fastest possible manner. All you then need to do after the insert is a full database backup with no need to worry about transaction log back ups.
Rick.