So symmetry works in HD Geometry scultping mode but it doesn’t allow me to have symmetrical safe areas. Is there a way to invert the safe area or create two separate safe zones? I don’t want to have to sculpt on the hands twice and they are in Tpose and so the safe areas doesn’t extend far enough to use symmetry.
I just keep solving my own issues. Hopefully they’ll help someone else with my clever titles. 
To solve this for hands, you hide the body and arms and then position the hands in space so that they overlap. Then when you put the cursor over the hands and press the ‘a’ key for HD mode both hands will be in the safe zone and you can use symmetry in HD sculpting mode then.