I wouldnt think there would be an issue building out of aluminum if you had a decent grade of aluminum? I would be concerned with warping from heat and the ability to weld it together. Might be slightly lighter but I don't know if the savings would out way it.
I know there is a thread on here somewhere where someone built a two vessel system (electric) on a kitchen rolling cart. Pretty clean and "light" looking.
Most people build their stands to hold the weight IOT upgrade to larger sizes later...imo.