I am sorry to say but you do not seem qualified/experienced enough to plan this venture. Get someone experienced to give you a hand and use them to learn how to do it the professional way. They will consider not just fuel burn but fuel prices at different stations, the need to tanker or not, Flight time limitations, tech stop costs including handling and landing charges, overflight permits, enroute alternates, etc, etc, etc. They will save your operation tens of thousands....
if I applied reserves as per what is writ plus my own 2.9T, actually, my 2.9T is my absolute come hell or high water figure that I will never be false to
That is an utterly meaningless statement, specially as you do not even seem to know how many miles or minutes that will give you for an empty A320. What you need is to actually work out is how much fuel you will need under realistic scenarios based on congestion, holding, usable alternates, approach aids and weather. 2.9 tons might be too much or not enough depending on the circumstances of the day. For example if you are planning a route significantly away from suitable alternates the minimum fuel will be determined by the depressurization case where you will need to fly for an extended period of time at 10,000 feet to reach a suitable enroute alternate