I have a couple of rust spots along the lower extended cab panel on both sides. I don't have the $$$ right now to get it fixed and have the truck repainted (which I'd eventually like to do). However, I'd like to do something now that will inhibit the rust from spreading in the meantime. I am thinking about wire brushing or sanding the current rust spots and then applying something like rustoleum as an intermediate measure until I can get the spots repaired and painted.

What are your thoughts?

I have a spot like this on both sides of the truck:

 

I'd recommend hitting the spots with some OSPHO then prime it.

 

It looks as though it's rusted through with how much flaking and bubbling its got. You might be better off waiting a bit till you can get a patch put on and then if you have to just let it sit in primer till you can afford paint.

 

The only way to truly stop rust is to cut it out completely. So the patch option is the best and only truly effective route. Anything else you do would only be a bandaid and delay the process not cure it, some better than others.