I'm wondering if this would work. Warning: I couldn't get much farther away from "tested code" while still writing some code.

package Net::SMTP::SSL;

use base 'Net::SMTP';
require IO::Socket::SSL;

@Net::SMTP::ISA = map {
  s/(IO::Socket::)INET/${1}SSL/;
} @Net::SMTP::ISA;
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Just curious. ;-)