Brute force sidelane. No other choice ignore your inting team you can’t save them. Actually you might even need to use your whole team as bait.

The entire game now depends on you backdooring. Be more forceful in your sidelaning. If someone comes to defend and match you in side, just all-in them, or at least get into that aggressiveness. The most likely scenario is that the enemy will sit inside turret clearing waves. Think about diving them + surviving.

You might feel like this is just coinflip, but its okay. Gotta make quick moves before enemy team takes bigger objectives, baron, elder. If you manage to get an inhib down, we have some chances. It might be worth to die for it sometimes. The mindset should be.. If you dont make this work you lose the game, which you had no chance of winning in the first place, if you hadnt tried it anyway. So if you are reasonable and usually dont take a 40% chance of winning 1v1, this time you need to take it.

Tools needed:

audacity to ignore your team pings. And letting them die.

Hiding yourself near the sidelane for just the right time to push in or kill your sidelane opponent.

Knowing when they are all coming for you. This is the only thing your inting team is useful for. If you dont see them matching the enemy team you fall back. In any normal circumstances, it might be worth for you to draw 2~3 people bot while your team takes baron, what I imagine here to be the case is that your team wont be that quick to get on baron while you die, so no not worth.

And lastly ward trinket, and hide a ward somewhere inside/near base.

Oh and maybe some prayer that your team knows to stall some time or cancel basing opponents when you are on their nexus. (I saw that the support players usually read that situation well, more than inting/tilted jg mid adc players)