For off the saw filing, I put an old 16" Stihl bar in the vice and let the loop droop below and weight by hanging a bucket off of the loop with a C- clamp. Holds things just fine, and advancing the chain just takes a lift on the bucket. I file one handed and get ahold of the chain with the off hand though.
One of our members, "Tree Machine" went to all kinds of tinkering, and developed a gizmo(Chainmeister) that tightens up the loop on a bar in a vice, and takes about 3 seconds to get the loop on and off. Last I knew it was in production and carried by one of our sponsors.
I got to tinker with the Prototype, and it was slicker than snot on a doorknob, but havn't gotten hands on a production unit yet.
I'll go see if I can't find a link for ya.
ETA:
Found it!! Chainmeister at Tree stuff.
Tree Stuff - ChainMeister Filing Device
Check out the Vids too, as they explain the thing better than I could.
Crazy Jim the "Tree Machine" really put some thought into the thing.
Stay safe!
Dingeryote