Retro-rockets.
I see a Dymaxion.
How thick is the aluminum? Will it be compound-curved? I've only worked with samples of PolyMetal but I like it. The thermoplastic core would provide the thermal and acoustic damping Christ mentioned. It come in 3mm and 6mm with .007 aluminum skins. There is a MaxMetal product with thicker skins, single-sided PolyMetal and so forth.
Tesla apparently makes their side intrusion trusses with nested corrugated pieces (cribbed from NASA). You might put a layer with horizontal and/or vertical corrugations behind the skin.
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Since the stock torsion bars are about 200% of your requirement, just remove the upper grub screw at the center of the torsion bar and it will float freely and act as a stiff ant-roll bar...I think. And if you want to throw money at weight problems, the steel front torsion beam is available in aluminum (for offroad use in Calif.) as a sand buggy part.