radiosity render over previous vertex colours

I have a mesh with coloured vertices and I would like to render it using radiosity. However, as the radiosity result is also saved into vertex colours, my previous vertex colours are discarded… is there a way of keeping them? I thought about writing a python script to save my vertex colours previous to the radiosity computations, but this wouldn’t work because radiosity modifies the mesh…
thanks in advance!

maybe there’s a way of converting the vertex colours into a texture? I could then map the texture over the radiosity-rendered model?
thanks in advance for your help!

You can bake the vertex colours to a texture: