If you're going to use PL/SQL, why not set up a cursor over the customer table sorted by dbms_random.random, then in the loop take first name from the first row, last name from the second, address from the third, etc. - then start again with the first name from the (say) sixth row. This will be random and will protect the anonymity of the customers (if that's an issue).

This will give you about 10'000 rows - repeat ad-lib (don't reset the seed) if you need more.