Also, make Austria offer the territory now instead of what they offered (after the war). Vienna planned on double-crossing Italy with the proposal (get Italy in the war, renege on the promise later) and the Italians knew it. Thus, immediate transfer of power.
Good luck getting the Austrians to agree, though. The Germans barely managed to get the OTL promise out of Austria, even with the Austrian mauling in Galizia and the planned double-cross.
And yes as i said trust between the two were not really much, for this reason Kaiser Willy pledged his personal assurance for that and proposed to make all pubblic; better if there is a timetable for the passage and not a generic after.
With a little of hindsight one can say that after WWI if the A-h leaderships suggest another round so they can safely renege a trety the only thing they will get will be a bullet in the center of their head from the troops and a socialist revolution in their hand, with Italy probably grab even more (so to protect the italian minority and battle the god-forsaken socialist/communist

).
More realistically it's an hard pill to swallow but Giolitti and the parlament can be convinced (expecially if a little effort is done for support this in the press) in taking the risk, expecially if there is the assurance/feeling that Germany will not intervene in aid A-H and the war will still last some time.
Regarding A-H how she emerge from the war much depends on how the conflict last. The longest the duration of the war is, more the thing become complicated in the aftermath (death, crippled, debt, economic turmoil, lost of credibility of the ruling class, socialisti/communist inroad), regardless of who win and lose, and A-H is the less equipped to resist them; contrary a quick enough victory can give the goverment enough clout to implement reforms for the long ride but things will surely change and the day of the Hasburg rule are numbered (they will probably become just like the British monarch now)