OP how do 'you' feel when coming down from AMPS? If you feel awful on the comedown from amps then plan it so your not coming down from them when you want to still be partying.
MDMA and then a redose would be better for you - if that would give you the energy for a full night of raving, only you know.
If you want a full night of raving regardless of the outcome then Start on the MDMA - then dose your Amp and final dose of MDMA. This way you will have clean ride for the start of the night and a more energetic finish - you will come down when the event finishes. (small dose of amps just as a energy boost)
If you do it the other way around you may find the lack of energy from the amp makes you feel really tired /heavy and no amount of MDMA will get you back up and dancing.
I think that not going to comedown from amps before the party ends is not hard too achieve, but your "schedule" seems logical as I wanted clean ride. I could even take small amp after both MDMA doses. That would keep me up til the and of the night.
I am just thinking, if its speculated that dopamine is making damage to serotonin "cells" when they are depleted from serotonin, it looks like amp would make even more damage in low-serotonin (MDMA comedown) phase?
I would really like the most to do it with MDMA only, its just that I am trying to be responsible about that neurotoxicity thing as I never did when I was younger and everybody is saying that you cant get much longer roll with redosing. I dont have to really be high all 12 hours. I could let first 2 hours to pass without anything.
The other thing is event schedule

There are concerts in first few hours and then "partying"

so, i should stay "clean" for first 2 hours and then dose mdma, I dont want it to end too early.
In the other hand, I guess total ammount of MDMA should matter... and if I understood correctly, "forcing" oneself to roll again while coming down could be harmful as neurotransmitters are already drained and fragile...So it should be somewhere around peak. I am concerned about long-term damage not about hangover. If you stay in some "intoxicated" state longer, its logical that your hangover will be crappier. Thats something I often do with alcohol, survive the hangover and I dont drink for some period. I get over it.

Its just that nobody told me "Do not redose the same ammount of vodka you drank in first 3 hours, and do not redose after 5 hours or so, dont try to get drunk again when it wears off"

I know.. different mechanisms for different substances but you get the idea.