I work at a concrete company...so we have these 300 gallon fluid totes for chemicals just laying around... then it came to me....why not turn one into a roof rack! They are light weight tube aluminum frames, you could cut one side for a small rack or two sides for a big rack....these things can be found cheap or even free sometimes. They look like these:
300 Gallon Tote/Tank - $85 (Old Forge) for Sale in Scranton, Pennsylvania Classifieds - AmericanListed.com
300 Gallon Tote/Tank - $85 (Old Forge) for Sale in Scranton, Pennsylvania Classifieds - AmericanListed.com