Why not two presenters (at the same time)?
As a one off LLS guest presenter, Steve Coogan would bring the house down, potentially even the country

Re Tommy Tiernan, the deeper he gets inside the RTE culture the more he would have to control one of his main comic assets which some people interpret as offensive.
Anyway, how likely is it that RTE are going to risk an embarrassment with TT? He already is a good earner for them, is cocooned from RTE ethos to a degree, he's carved out a very successful niche for himself with the challenging (blind) interviews on stage format.
It has to be Miriam.