Greetings all,
one rather hokey/simple solution might be to declare the default values in a hash then validate your input rows before you execute the statement handle.

#set your defaults for the table in question
my %defaults = ('col1'=>'col1_default_value','col2'=>'col2_default_val
+ue'...);#you get the idea.

#your data set
my @to_insert = (
      { 'A' => 1, 'B' => 1 },
      { 'B' => 2 },
      { 'A' => 3 },
);

#clean it up for the statement handle
foreach my $rec (@to_insert){##each record to be inserted
    foreach my $key (keys %defaults){##each field in the record
        unless(defined $rec->{$key}){
            $rec->{$key} = $defaults{$key};
        }
    }
}
[download]

A bit cheesey I know but I hope that helps.
-injunjoel
_{Side-Thought: Have you tried inserting a "" or '' for a bound column to see if the default value gets inserted?}