Same height just narrower. No problem I'm doing the same thing...
You can run different sizes on the rear for short trips in the dirt, the tires will just slip and it will pull the the side the 28" is on. I wouldn't go too fast or far that way however.Could you use a factory front wheel with the 28 inch tire as a spare if all your other tires are 32’s. Im talking like put it on the front and don’t engage 4wd. Kinda like a limp back to camp type thing. I know running different size tires is a no no on the rear. They must be the same size. But the front as long as you don’t engage i4wd should be ok?