Overloading the PLMs can be done with as few as 2 Power Bombs if they are placed precisely. Place them two ledges above the item - to the left of the morph tunnel item. It is important that they are placed on either of the flat tiles, not the sloped tile on the right.

Requires:

"canPowerBombItemOverloadPLMs"
{
  "notable": "G-Mode Overload Speed Blocks then use Global Crab"
}
"h_navigateUnderwater"
"h_artificialMorphPowerBomb"
{
  "or": [
    "h_artificialMorphPowerBomb",
    {
      "and": [
        {
          "itemNotCollectedAtNode": 7
        },
        "canRiskPermanentLossOfAccess"
      ]
    }
  ]
}

Dev note: An item is expected at node 6, otherwise this strat isn't useful. It takes 2 PBs to overload PLMs, or only 1 if both items are uncollected.