For each routine in Test::Utils::Dump couldn't you just do something like:

sub d0 {
 if($ENV{MYMOD_DEBUG_LEVEL} >= $my_level) {
   doThis;
 } else {
   doThat;
 }
}
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In general, it might help to name your routines with a common tag so they are easy to find. For example my_debug_d0.