If you make your scripts into modules, your script can be 2 lines

use MyScript;
MyScript->run;
[download]

then you could run using

perl -I/opt/scripts/development -S script.pl
perl -I/opt/scripts/development /opt/scripts/development/script.pl

perl -Mlib=/opt/scripts/stable script.pl
[download]

but better to write lots of tests and use make test or prove when developing. As example see tracker (App::TimeTracker).