The barrier detects
movement, there's nothing to support the idea that it can't sense Susano'o arrows moving towards him. The scan you posted even says he can feel the activities of those inside the barrier - so Jiraiya can sense Sasuke loading up an arrow if Sasuke is within the barrier (most likely case, since the barrier is huge):
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If Sasuke fires the arrow from outside the barrier, it crosses the barrier's border and alerts Jiraiya that an arrow is incoming. Worst case scenario, Ma and Pa (who are perfect sages with SM sensing) warn him that a Susano'o arrow is coming. It doesn't matter anyway since Sasuke won't know where to aim the arrow if Jiraiya is in Ma's dust cloud.
Also - sharingan can't see through the dust cloud. Sharingan distinguishes chakra by its color, but the dust cloud itself is infused with chakra, so Sasuke can't see Jiraiya's whereabouts within the cloud. It's the same reason Kakashi's sharingan couldn't see through Zabuza's mist.
Jiraiya can shoot the burned areas of his hair off with Kebari Senbon.
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Amaterasu can kill a summon, sure - but if there is a toad crashing down on Sasuke and Sasuke uses Amaterasu, it is still falling down on top of his Susano'o; and if it doesn't crush Susano'o completely, it surely puts a tremendous strain on Sasuke and sinks him into the swamp below him. Raiton on Sasuke's level isn't going to dry up a swamp of that caliber. I question raiton drying up this swamp at all, since it's not a normal earth-based technique (it's more liquid than solid. Katons would be a better option for drying up the swamp.)
Susano'o isn't tanking
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It would literally melt the Susano'o. Susano'o has shown to corrode and start to melt against extreme temperatures, such as lava release
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or Boil Release
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. Even if it does not actually melt the Susano'o, it will still kill Sasuke. The oil and fire will completely engulf Susano'o and the heat produced by the flames will make the temperature within Susano'o rise to be very hot, since there's no flow of air in or out of the Susano'o due to the flames and oil - the exact same effect as an oven. Sasuke will overheat and die, literally trapped in his own Susano'o.
Also you didn't address my other methods of attack.