I have used surplus bakers racks, and they worked pretty well. One problem is that some of the light weight ones (over time) will sag and deform under heat when weight is applied.
Don't learn like I did that a cheap rack won't prevent something from falling to the ground and ruining the day for everyone but the dog.
Generally speaking, almost anything metal can be used that has is non-reative, and has been
properly cleaned. Also, the racks don't have to be limited to metal. Several of the sausage makers here at SMF actually use wooden dowels regularly and their results are excellent.
I have seen people cook using almost anything to act as a support mechanism. Chop sticks, hub caps, rebar, pie pans, cardboard, pallet slats, baling wire, etc. so don't be afraid to experiment.
One of the best meals I ever ate was shish Kabobs cookedover an open fire, on wire coat hangers out in the middle of nowhere in Turkey.
There are many different kinds of racks available commercially at a restaurant supply store, resale shops, or other places. Check them out, hopefully they can fit your dimensions.
Good luck with your quest.