I've got my PD cockpit area apart at the moment. ( I presume you are refering to the later model PD), and it's a little bit of a nightmare. I'm actually replacing the upper cockpit/speedo panel on mine, so it is bound to be a little bit more involved.
I've took the whole lot apart, including the upper crashbar, and the upper panel that houses the Speedo ect, it was still a nause getting the actual light unit out,..well, fiddly, y'know?
You WILL need to remove both upper side panels, which means removing the indicator heads from the stalks...
I'll be reassembling it tomorrow, so I'll check if there's any shortcuts you can do. Fire any questions at me this evening if you like.
Having a set of 'wobbly' Allen sockets on a 12" extension bar is the way forward. But wouldn't suggest you buy 'em..I needed a mortgage to buy mine.