To clone the repo without hi-res photos...

mkdir gmss
cd gmss
git init
git remote add github git@github.com:gmss/wordpress-site.git
git pull github light

...then configure fetch as below.

To remove hi-res photos from a clone...

git branch -r -d github/master

...then configure fetch as below.

To configure fetch type

vi .git/config

and change the line

	fetch = +refs/heads/*:refs/remotes/github/*

to

	fetch = +refs/heads/light:refs/remotes/github/light