I would be more than happy to help out as well.
Who would appoint the group? I'm not sure how it could/should start. Is this something Forumer needs to start or is it something that can be started by a Support Team member or someone else?
I mean it would have to be strictly controlled and heavy penalties if the temp admin should do anything to damage the forum they are looking after. Maybe deleting their own forum as a penalty.
Of course there are pros and cons. The worst con I can think of is having a temp admin and coming back from vacation to find your forum is gone and you have been banned. That would be the worst case scenario of course. Hence the reason for heavy penalties.