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.