If you need a wider base, you can use wire to attach a wider base to whatever narrower one you end up with. For example, I have a milk crate mounted to my rack. The rack is much narrower and the base of a milk crate isn't very sturdy, so I took a piece of wood and attached it to the rack, then attached the milk crate to both. A plastic cutting board from a dollar store would work too, if the ones near you have one that's a good size and decently thick but not too thick. Mine did, but the wood was free, so I went with that.
Then you can use a rack of any width and focus on the quality of it.