Just letting everyone know what you can do with your D4 with a little time and patience and a little help from this and other forums.
Since I picked up my D4 MY11 SDV6 HSE about a month ago, have done the following:
Fitted a 2nd battery under the bonnet with a Traxide kit. Managed to empty the 2nd battery tray and install an Optima yellow top battery. Installed 2x 12v outlets in the Cargo Area from this battery, as well as fitted an Andersen plug at rear for running Caravan Fridge while travelling. (thanks to Drivesafe for his instructions and for answering a few questions by phone on a Sunday Afternoon)

Installed a Prodigy P3 Brake controller for the Caravan. (Thanks to Sniegy for his detailed post on how to do this.)

Transferred the Centre Console Cooler box from my D3 to the D4. Hard wired this with fuse to the 2nd battery.

Installed a GVIF Video interface. This allows me to connect the Rear View Camera on my Caravan to the HSE Sat Nav Touch screen in the D4. While I was at it, added another Video Input next to the Audio Aux input at the rear of the centre console. Never know when I might want to connect another video source to the Sat Nav Screen. (thanks to Pete from Bellautos and HIDS4U over on Disco4.com for their help). Can access either video source at the press of a button.

Never done any auto electrical work myself before, but managed to get all of the above working first go. And with care and patience, no damage or scratches to any of the console or dash components or panels.

Also transferred Roof Rails and Racks from the D3 to D4, but this was pretty simple compared to modifying the Sat Nav to handle other video inputs.

Probably spent many many hours researching all of the above and printing out instructions before I started, then about 12+ hours over a couple of weekends actually doing everything. Took it very easy and slow, thought about what needed to be done, took everyone's advice, top result and no problems/damage. Added benefit of knowing what to do to fix it if any of it stops working.

discomaniac