Four consecutive climbs is impossible without a loop around the volcano that means a lot of flat/rolling/hilly terrain in between because there are only two "passes" available (at località Mareneve on road to Piano Provenzana like in 2011 and at Rifugio Sapienza). The hardest stage possible would be start on the north coast with some climbs in the Madonie/Nebrodi/Peloritani (the range known as Appennino Siculo) then approach Etna from north, climb to località Mareneve, climb to Rifugio Sapienza and MTF at the dead end Osservatorio Astrofisico (the climb used in 2018).
Anyway I think the idea of the full climb MTT is for a second or third week stage, but because a 30+ kms MTT it's madness at the beginning of the race not for the weather that in Sicily could be an issue only in a very but very extreme scenario even if you go at 2.800 meters.
Anyway I think the idea of the full climb MTT is for a second or third week stage, but because a 30+ kms MTT it's madness at the beginning of the race not for the weather that in Sicily could be an issue only in a very but very extreme scenario even if you go at 2.800 meters.