As you said, these are all the pieces already. If what I'd figure is your question it's easy to answer:
"How much damage would I do if I fire for $Length time?"
$Length * $RoF = X rounds
X rounds * $damage = gunDamage
X rounds * $DOT% = avgDotAmount
DoTs are smart in this game, they all have their separate timers and can stack independently from one another. This makes the damage as intuitive as possible:
dotDamage = avgDotAmount * ticks(element)
totalDamage = (gunDamage + dotDamage) * multiplier(element)
As this was far too easy to answer, I can only assume your question would be like
"When can I stop firing, knowing that my DoTs will kill the enemy?"
To which the answer would be "Never, unless the target isn't currently affected, then keep firing."
To us human player at least; for all the data is there in the fountain of numbers that spew from the target you are perforating with bullets. Would we be perfect computers, we could see when a new dot starts ticking(it wouldn't have a previous tick before it) and thus know exactly how many ticks are left. Being human, all we can say is "it's on fire" or "it's not on fire." This makes knowing for SURE your target is going to die impossible, the best one could do is make a normal distribution graph(wiki) with the probabilities if your target will die.
If that's really what you'd want, I could run it through some model, but it's still gonna be a pretty useless graph. Input the specific gun and skills you're using, and you could get a graph with probabilities mapped vs dotDamage. Even if you could watch that while shooting things, you can only guess how much health your target has left.
If instead, and my final guess, the question would be "How much do I overkill?" that amounts to the same, as that is also "Amount of dotDamage still to be done."
Best Answer
Firstly you will need to open your save into Gibbed's Borderlands 2 save editor and move your way to 'Raw' to edit your characters Raw Data.
Now scroll down until you see
MissionPlaythroughs. When you find, it navigate your way to the arrow that will open up the collection window. Image below will give assistance if needed.Now that you've opened up the collections list you will notice 3
MissionPlaythroughDatathe first one is Playthrough 1 (Normal Mode), the second one is Playthrough 2 (True Vault Hunter Mode), and the third one is most likely the 'Something Interesting thing' that Gearbox Is planning on when they raise the level cap which will be a Playthrough 3 no doubt. Depending on what playthrough you're on, choose from 1 of 2 existing options available since Playthrough 3 has no data yet. Once you've clicked one of these navigate your way to theMissionDatacollection arrow. Image below will assist you if needed.Once you're in your quest information you will notice a lot of quests. There are two ways to look for the quest you REALLY want to edit, #1 is looking to
missionon the right this will show you the name or "Codename" of the mission, and #2 is seeing if the mission is Active, Not Started, or Failed. Once you've found the mission you want to edit look toStatusand change the mission toReadyToTurnInif you want to instantly complete the mission. If you want to complete a few sub objectives, or objectives you will need BL2 to reference the number of requirements. You can access these options by looking toObjectiveProgressandSubObjectiveSetIndexesopening one of these will show a set of numbers depending on the quest.Like I said before you will need BL2 or a wiki to reference the 'complete' number of the mission requirement. Once you have something to reference from you can then modify the numbers and set a certain objective to 'Complete' some missions may be different though whereas 0 Is incomplete and 1 is complete - remember that! Image below will give assistance if needed.
It may take some time to get a hang of, but its really not that hard if you think about it. It also comes in handy if you have a quest that you're having a really tough time with such as; finding rare monsters or killing a hard raid boss. It also comes in handy if you're making a save from the ground up.
Source: Borderlands 2 How to Edit Quest Data [PS3/360/PC] by Seth | gamecrave.forumotion.com