Here is an example of solar panels that we have fitted to a caravan.
They were 2 x 160W mono-crystal solar panels fitted with a Stecca PR3030 charge controller.

Once fitted, only the charge controller is visible in the van
and one piece of wire inside, near the ceiling.

Everything else can be neatly added to the vehicle wiring inside the bed box.

The next two photos below show that the solar panels are producing 3.5 amps in winter sunshine in January.
In summer they should peak at around 20A.
The second photo shows the state of charge percentage and bar graph.
The total cost for this fully installed in January 2019 was £780.