I have leather lined steel shackles that I can connect with chains and padlocks. Same for a collar. (allthough I won't attach any chains to her collar)

What if I leave her enough slack in her chain connecting her to the wall for her to reach the back yard in case of emergency when she is left alone for a while. Her ankles and wrists shackled and her feet high heeled.
I am not so sure about leaving her gagged while unattended, or do completely safe gags exist?