In reply to John2:
Ikea bags rule for this. Save time, faff and wet rope.
hanging belays are not hard, they are just the same as any other trad belay.
The rope is easy to incorporate, and makes sense to do so. A cordette or large sling also help, as the first down will need to Un weight the ab rope to enable the second down to be able to abseil.
Personally:
At top, flake ropes into ikea bag, tie ends onto bag in a way you know which to tie into for climbing.
Leader abs down using shunt/ropeman/ Prusiks.
Sets up hanging belay with big sling, maybe even makes space for their 2nd to easily stand next to them.
Second comes down, clips into belay, if using shunt or ropeman, this can be left on.
Ikea bag hung on belay, near one of the pieces of gear is easiest, if it's too high, a sling is useful make it lower.
Tie in, lead etc.
Set top belay up, pull up ab rope, belay 2nd.
A set of walkie talkies can really help if your not practiced and familiar.