High contrast/visible colors for google maps

I am creating some custom markers for an application that uses google maps

They stand for a tow truck and a broken car.

An important constraint is that they must contrast with the map bellow, in many situations. That excludes, for example, light blue (low contrast with water) and light green (low constrast with parks)

In the example, we have a tow truck (that I am happy with) and a broken car (that I think has poor contrast).

What colors would be a good fit?

I understand there exists some color theory in design, but I know nothing about it. An explanation with good pointers to that would be expecially invaluable.