BBQ design: calculations

Some quick numbers from the hardware store:

They sell aluminum square tubing, 25 by 25mm across with a 2mm wall, at 5.05 Euro per meter.
Such tubing weighs 496.8g per meter.

I need 6x40cm and 6x80cm for the support structure, which is 7.20m in total, 36.36 Euro, weighs 3.577 kg.
I need 2 sheets of 80cm x 40cm x 2mm, 2 of 80cm x 10 cm x 2mm and 2 of 40cm x 10cm x 2mm. That's a total of 1760 cubic centimeters, weighing 4.752kg.

In total, the BBQ will weigh more or less 8.5kg.

I'm also considering using aluminum for the grills, since it resists corrosion remarkably well.