... copying every field in the object by hand to the new object.

Maybe (untested):

use Scalar::Util qw(blessed);

sub clone {
    
    my $self = shift;
    
    my $clone = blessed($self)->new or die "clone failed ($self)";
    
    @{$clone}{keys %$self} = (values %$self);
    
    return $clone;

    }
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Of course, this is still essentially "copying by hand" with lotsa potential pitfalls.