I wonder how the community would react if an Arbitrator said, I want to take a 6 month break but not give up my seat entirely; and would Jimbo appoint a replacement for that 6 month period.
There is precedent for resigned arbitrators being allowed to retake their positions any time until they would have expired normally, even after a replacement has been elected (not appointed, and not just for the length of the break, so the original arbitrator returning would increase the size of the committee temporarily). I don't believe anyone has actually done so, but Mindspillage and Filiocht have the option to for another year (according to the timeline on WP:ARBCOM).