Turns out my brother has opted for a gold wing with a chair for less than this guy wants for his XS, brother didn't end up looking at this one so I can't offer any info on it.
Just an update on this: brothers gold wing deal fell through (seller changed his mind) so he did go and take a look at this one. Engineers certificate all legitimate, unit is very "untidy" (brothers words) and it was only running on 2 pots so couldn't be taken for a test ride, only fitted with a hydraulic brake on the chair (NSW RMS requires a remote mechanical handbrake also be fitted to the chair)
The owner says the bike itself is ex police and that's the reason it has the twin headlights but he couldn't verify this, I'm guessing that if it was the reason then I'm sure it would've been done a hell of a lot neater than it is. My brother ended up walking away and didn't try negotiating the price as it would involve way too much work to make it legal and reliable.