You can specify table names on the command line one after the other, but without wildcards.
mysqldump databasename table1 table2 table3
You can also use --ignore-table if that would be shorter.
Another idea is to get the tables into a file with something like
mysql -N information_schema -e "select table_name from tables where table_schema="databasename" and table_name like 'bak_%'" > tables.txt
Edit the file and get all the databases onto one line. Then do
mysqldump dbname `cat tables.txt` > dump_file.sql
To drop tables in one line (not recommended) you can do the following
mysql -NB information_schema -e "select table_name from tables where table_name like 'bak_%'" | xargs -I"{}" mysql dbname -e "DROP TABLE {}"