Whatever you choose, I think you should add a skeleton distroprefs file to your distribution. Distroprefs are used by CPAN.pm to set environment variables, command line arguments or answer interactive questions while configuring, building and testing the distribution. If the user does not like your defaults, then he can put this skeleton into his own prefsdir, made the required changes and could forget about it for future upgrades/installations.

A sample file looks like this:

--- 
match:
  distribution: "^CAPTTOFU/DBD-mysql-\d+\.\d+.tar.gz$"
pl: 
  args: 
    - --testdb=test
    - --testhost=localhost
    - --testport=3306
    - --testsocket=/var/run/mysqld/mysqld.sock
    - --testuser=root
    - --testpassword=something
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