It's not an answer directly to the question that you asked, but couldn't you manually massage the results after splitting?

my @clumsy_split = split /($re)/, $string;
my @split;
my $flag = 0;
for my $i ( 0 .. $#clumsy_split ) {
     my $field = $clumsy_split[$i];
     if ( $flag ) {
          $flag = 0;
     } elsif ( $i % 2 || length $field < $limit ) {
          push @split, $field;
          next;
     } else {
          $flag = 1;
     }
     $split[-1] .= $field;
}
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This won't give exactly the same results as a hypothetical split ( /($re)/ && length $1 < $limit ), $string—for example, if $re is /a+/, $limit is 1, and $string is 'aa'—but maybe it's close enough.