One option may be Vegas by Doobox. I quickly set up a demo (using 3 images with text overlay) here:
However there's a white border around it all (about 20 px) and I'm not sure why. (I'm very new to Foundry: probably user error).
You can see the Vegas stack with a regular theme here:
... but if there's a way to get rid of the white outline then this would work great (I think) for your needs.