Did this mod a while back but thought I'd share what I did and a few lessons learned along the way.
Fitted a car stereo unit to our Expanda-12 in the small space above the wardrobe door.
Tip#1 - check you can close the wardrobe door with face plated fitted to stereo before cutting. I ended up removing the small panel section of the wardrobe and cut the hole out using a jig saw. Panel was held in by a number of screws which were easy to remove; there were also staples holding the panel in which was a bit more challenging. I used painter's tape to protect the panel surface while cutting. Tip#2 - remove tape immediately after cutting hole, otherwise run the chance of peeling off some of the panel veneer. With limited options for locating speakers due to internal layout, I chose to make small speaker boxes and fitted them beside the valance over the window.

I had to relocate the valance slightly so that I had a even space each side to fit the boxes. This was simple as only held on by three screws. Got some cheap 4" speakers from JB Hi-Fi and ran the cabling through the cupboard into the wardrobe. Tip#3 - with this particular stereo unit, I had to connect both ACC and BAT+ wires to van DC+ to power up stereo. Still have to tidy up the wiring but have powered up the system and it gives good sound. Also fitted a pillar mount aerial.
Was a bit hesitant drilling through the van wall for the first time but it worked out well. Tip#4 - when locating the aerial, make sure the collapsed aerial does not protrude above the roof line in case you fit a caravan cover. Tip#5 – This particular stereo’s display is very bright even when turned off using the stereo’s on/off button. I ended up fitting a small switch in the 12VDC input line to turn it totally off at bedtime. This would also be helpful to reduce battery drain if free camping (which I’m not set up for anyway)
Fitted a car stereo unit to our Expanda-12 in the small space above the wardrobe door.

Tip#1 - check you can close the wardrobe door with face plated fitted to stereo before cutting. I ended up removing the small panel section of the wardrobe and cut the hole out using a jig saw. Panel was held in by a number of screws which were easy to remove; there were also staples holding the panel in which was a bit more challenging. I used painter's tape to protect the panel surface while cutting. Tip#2 - remove tape immediately after cutting hole, otherwise run the chance of peeling off some of the panel veneer. With limited options for locating speakers due to internal layout, I chose to make small speaker boxes and fitted them beside the valance over the window.

I had to relocate the valance slightly so that I had a even space each side to fit the boxes. This was simple as only held on by three screws. Got some cheap 4" speakers from JB Hi-Fi and ran the cabling through the cupboard into the wardrobe. Tip#3 - with this particular stereo unit, I had to connect both ACC and BAT+ wires to van DC+ to power up stereo. Still have to tidy up the wiring but have powered up the system and it gives good sound. Also fitted a pillar mount aerial.

Was a bit hesitant drilling through the van wall for the first time but it worked out well. Tip#4 - when locating the aerial, make sure the collapsed aerial does not protrude above the roof line in case you fit a caravan cover. Tip#5 – This particular stereo’s display is very bright even when turned off using the stereo’s on/off button. I ended up fitting a small switch in the 12VDC input line to turn it totally off at bedtime. This would also be helpful to reduce battery drain if free camping (which I’m not set up for anyway)