This double-legged tether from Kong: Kong Double Expandable ORC Tether w/ Quick Release
...is ISAF approved. It can be unclipped with one hand, yet requires a very specific grasp in order to disengage the safety.
It has a short leg and a long leg, so that you can choose the best one for the task at hand. It also lets you "hop" from point to point while remaining clipped on.
It also retracts due to the elastic sewn inside the cover. I've been very happy with it so far.
As for your jacklines, you may need to re-consider how you've run them, if they are causing interference.
Mine run nearly all the way to the bow, hiding in the crease between the cabin top and the deck. This keeps them from being underfoot most of the time.
You might consider a single jackline, run on the centerline.
All boats are a little different, with different layouts and will require some experimentation. Maybe your movements just need a little more practice and forethought.
In any case, two thumbs up on your solo sail, and tethering on. In spite of the inconvenience, it kept you onboard and we're not reading about your unmanned boat being found floating around.
Oh, I almost forgot: You should contact the SFBaySSS (Singlehanded Sailing Society). They will probably have some great advice for you.
Singlehanded Sailing Society | San Francisco Shorthanded Racing