What is the best way to get the underside fully cleaned (aside from fixing those pesky oil leaks)?

During an alignment I took the opportunity to snap pics after I cleaned it up and degreased with Simple Green. Had to reach in there well while I was in the car wash bay so I could spray the underside generously, wait a few minutes as I cleaned the wheels and washed off as I rinsed the car. By that time the degreaser will have taken effect, but it seems something stronger is needed.

Any thoughts?

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