Raycasting in render depsgraph context?

For an exporter / render plugin I’m trying to raycast from grease pencil stroke points to the camera location, but this should happen in an evaluated render depsgraph.
Currently I’m using scene.ray_cast and this works not correctly.
The reason for this is, that scene.ray_cast uses internally the evaluated depsgraph from the VIEWLAYER.

The only way I can currently imagine to make it work is joining all mesh objects into one mesh object and using the object.ray_cast function with the render depsgraph.

Do I miss an other possibility to do this?