Just epoxy coat your metal, after the anti-rust primer, after several layers of paint. You'll have a nice water-proof metal surface.. provided you don't scratch through the layers.
If it was true that metal stands will collapse with a bit of rust... take a look at construction sites where the metal framework is in place... do you think they treat it that well completely before they put concrete around it?
Do you see the number of rusting ships still floating out at sea?
Metal will only become structurally weak if a substantial amount of metal has been CORRODED THROUGH (ie. HOLES) in the metal at critical joints before they become unstable.
Poor quality wood, on the other hand, may splinter if the wood becomes wet and dried up again, causing expansion of the 'pores' and with enough sidewards pressure (try rocking a wooden stand), may disintegrate at the joints.
Never never use fibreboard as a stand.
Only use Chengai wood, its oily in nature and therefore water-resistent to a high degree and very dense.
My 2 cents.