Have someone on your team who can 1-2 shot shrooms, preferably from range.
Have that person pick up Grez's Spectral Lantern or Hextech Sweeper.
Have them search for shrooms, using the item active to check bushes, you can hit the speed shrine, the bush on either side, and the path to/from bot lane with one active use.
Farm passively (including jungle) and try to get ahead of them.
And above all else: Do not, under any circumstances, follow any member of their team into an area that hasn't been scouted.
Don't chase. Don't even chase. Chase and you're dead. He is fast; faster than you could believe. Don't turn your back. Don't look away. And don't chase. Good luck.