This is doable. For LWP::UserAgent, the actual socket is in HTTP::Protocol and its subclasses. Those classes accept extra socket configuration from global @EXTRA_SOCK_OPTS. That’s where you can set LocalAddr and LocalPort.

Just do something like this: (code is tested.)

#!/usr/bin/perl

use LWP::UserAgent;
use strict;

push(@LWP::Protocol::http::EXTRA_SOCK_OPTS, "LocalPort" => "7000");
my $a = new LWP::UserAgent();
$a->proxy('http', 'http://ofgfw1.owfg.com:8080/');
$a->get("http://www.yahoo.com/");
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When I was testing, I added extra code in LWP::Protocol::http.pm after the socket is created, to make sure the local binding is correct:

print $sock->sockaddr(), "\n";
print $sock->sockport(), "\n";
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And this passed.