I think you might need to learn how the Viper Sight gauge works.

Starting with the basics, looking at the 'inner' colour, nothing lit up means it is the first step of the combo, with the orange lit up, that is the second step of the comb, and also where your buffs are, once it is lit up with orange and blue, that is then your last step of the combo, or your finishers.

Onto the glow on the outside. No glow means it is the first step of the combo, so easy enough. Second step, if you have no final combo buffs up, then both sides will light up red. It doesn't matter which one you use here as no finishers are getting buffed. If one side lights up red, then that is the one you want to use to get to your buffed finisher.

On the last step, again, if both sides light up blue, then it doesn't matter what you do. However, if one side lights up blue, that is your buffed finisher and it should be the one you use. As for knowing which ones are flank and which ones are rear, there are a few ways to tell. First, all flank combos come off of the damage buff and all rear combos come off of the speed buff, so knowing which one you used helps in that regard. The next is looking at the colours. The combo ender buff will either be mostly green or mostly red. All green buffs are flank and all red buffs are rear, these also coincide with the actual hotbar icons as well. The last is just having to keep track. They will always alternate between flank and rear.

With all this knowledge, you could, in theory, perform the entire basic Viper rotation only looking at the Viper Sight gauge.

I could take it a step further and claim you could play the entire single target rotation by only being able to see 3 icons. Dreadwinder, Serpent's Ire and another just to see the GCD rolling. Everything you need to perform Viper is in that gauge.