Getting disc path to a Matrix File without using a tag pair

Question

I'm currently forced to do this to get a disc path that I can send to CE Image for resizing:

{exp:ce_img:single src="{product_carousel_images limit='1'}{slide_image}{rel_path}{/slide_image}{/product_carousel_images}" width="320"}

I though there was a way to do something like

 {exp:ce_img:single src="{product_carousel_images limit='1'}{slide_image:rel_path}{/product_carousel_images}" width="320"}

But that does not seem to work. It'd be even better if I could do something this:

{exp:ce_img:single src="{product_carousel_images:1:slide_image:rel_path}" width="320"}

But that is a different problem.

For various reasons using remote images is not an option for us - we use a BasicAuth on all of our sites during development, and it a hit to performance to load massive images over HTTP then re-cache them, when they can easily be loaded from local disc.