Just follow the instructions with the unit for wiring the speakers
You will then have 2 live + leads to connect to the van If you don't go back to the van battery direct you will lose the memory every time you connect to the car when the habitation relay switches off the van internals
I would connect direct to the van battery using the fuses supplied with the CD/radio unit
The earth-ve is usually white in caravans
I would install the unit inside a roof locker either in a housing bought from a motor factors or in a wooden box made up by yourself
If it is a radio as well I would use a non boosted stick aerial on the side as I have had a problem with interference when using the boosted type
Hope that helps
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