The Radio needs to be mounted securely, I used an under dashboard mount which I fitted under a shelf at the front of the van.
The speakers can be easily fitted using speakers with a case / pod or by making mounting holes to take the speakers in the caravan structure (cupboards are only made from light plywood easily cut with a craft knife).
You need to find a switched live to deliver the 10amps or so for the radio and a permanent live for the memory circuits.
I managed to take a switched live feed from a lighting circuit (check that the cabling etc is able to take the current (Amps) required. Most modern vans will have a power isolation switch on a panel which turns off 12v to the Van so the radio will be off when leaving the van.
The hardest part of the installation for me was routing cables. I wanted the cables to be invisible by care fully routing thru cupboards and long the inside edge of shelves the cables can not be seen. The cables can be set in place with a glue gun rather than clips etc.
The radio I fitted came with an ISO connector and adaptor to bare cables which made the job easier just needed a choc block to make good connections to speakers and power.
Now my caravan has a better Radio and Music player than my car.
I fitted the Wharfedale ICS182 Bluetooth In Car Radio, was at a good price and had loads of features, SD card, USB, AUX (handy for mp3 players) and CD player that appears to play most formats of CD.
Switched +12v Live with suitable fuse
+12v live from battery for Memory
Ground connection (-12v)
Remember use the correct size fuse and cable!!