This is possible to do without taking a second hit: Enter the room in a jump, then shoot down to open the door and land in the doorsill.

Requires:

{
  "obstaclesNotCleared": [
    "A"
  ]
}
{
  "enemyDamage": {
    "enemy": "Sm. Sidehopper",
    "type": "contact",
    "hits": 1
  }
}

Exit condition:

{
  "leaveWithGModeSetup": {}
}