I finally took the time and built the courage to drill into my van and install these side skirts. Just simple ABS strips, VHB tape and push fasteners.
They hang down just a hair higher than the front splitter. Exhaust and fuel tank stick down about 1/2-1" below the skirts still.
Don't know if or what effect they might have, hopefully keep some air from hitting the back tires. I think it looks pretty good too.