2x4s with u-bolts around the side bars? cut some tubing (old garden hose?) into 3-1/2" pieces, slit lengthwise and slide over existing bars for protection from wood and u-bolts. Presto: Ghetto cross bars.

(I also understand that used tires make great bumpers for parallel parking )

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83 300TD, 260,000 miles, aka "Dusty"
6 vehicles, 2 cup holders (both in the dump truck)