Insulation question for my own build.

I didn't catch that my awesome plumber didn't hold this main drain far enough off the concrete wall to get a 2x4 stud wall behind it to get my min R10 insulation from floor to rim joists. If I'm using unfazed R13 fiberglass, and have no plans on finishing anything in this area, can I stop the wall below the plumbing, and just wedge the fiberglass bats above it? Any other ideas, using the 2x4s and R13 bats that I already have?

I didn't catch that my awesome plumber didn't hold this main drain far enough off the concrete wall to get a 2x4 stud wall behind it to get my min R10 insulation from floor to rim joists. If I'm using unfazed R13 fiberglass, and have no plans on finishing anything in this area, can I stop the wall below the plumbing, and just wedge the fiberglass bats above it? Any other ideas, using the 2x4s and R13 bats that I already have?