Ok, i found my solution for now. It also works when i do the opposite inheritance : when Module::Starter::PBP inherits from Module::Starter::Smart.
So, i'll create my own plugin, maybe called Module::Starter::PBP::Perso. It will just be a copy-paste of Module::Starter::PBP, inheriting from MS-Smart instead of MS-Simple.
And anyway, i'll have to read the source code and change little details in the module, in order to add the creation of the ./t/My/Example/Class/01_unit_test.t file, as well as ./t/lib My/Example/Class/Builder.pm. And i'll try to add my Log4perl configuration stuff at the same time.
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I'm still curious on whether Dist::Zilla proposes something to do this.