I was going to recommend passing only characters that don't exist in iso-latin-1 to unidecode using a fallback handler to encode. It works, but I'm getting an error (Close with partial character.) when the file handle is closed, and I have no idea how to fix it.

Here's the code anyway:

use strict;
use warnings;

use PerlIO::encoding qw( );
use Text::Unidecode  qw( unidecode );

use constant FB_UNIDECODE => sub { unidecode(chr($_[0])) };

my $file = '...';

local $PerlIO::encoding::fallback = FB_UNIDECODE;
open(my $fh, '>:encoding(iso-8859-1)', $file)
   or die("Unable to create file \"$file\": $!\n");

print $fh "abc\x{201C}def\x{2013}ghi";
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