It looks like it already has a custom/homemade cover from the pic, or is that not your vehicle?
You could for sure make some. I have a 2012, so not sure if it's the same size, but if you need a template, I could scan them and email it to you.
I just pulled my covers to look. My part on left/driver side says:
Mazda
TE69 688F1
K3006
>PP<
and on the right says:
Mazda
TE69 688E1
K3006
>PP<
When I do a search for that, the closest I find is:
TE69-68-8F1C-02
at parts places like realmazdaparts.com
The site says it fits my 2012, so maybe that's the part number for the newer models, but that that piece is unchanged. *shrug*
The part is listed under Interior Trim/Rear Body/Outer Cover/Left & Right w/ and w/out Power Lift Gate