If your customer is running at least one XP Pro box, you could forward port
1723 to that PC and enable XP's built in PPTP server. Then from your PC you
could PPTP to your clients PC and get to that PC and any other device on his
network. The limitation is that it only supports one PPTP connection at a
time and of course he would need to leave that PC turned on but does not
need to be logged on. Not sure if that would work for you but thought I
would mention it as a possible alternative.
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