Looks like me and you are gonna be disagreeing alot in this area. Handling has nothing to do with fitting a tire, so that doesn't matter. I have a add-a-leaf up front and I clear the 35x13.5x20 no problem, little rubbing on the leaf spring because I didn't do a aggressive offset wheel( stock 0 offset). I test fit a 37x12.5x20 because I wanted to see how that would work, and they clear also,with still rubbing because of the offset of my wheel, but only on the leaf spring. So unless I have a one off excursion, which I don't, I know i'm not mistaken. Pics are available for reference.What...sorry thats just wrong about Excursions...
It will take more lift not less with a Excursion. I have helped hundreds of excursion owners all over the country fix the handling problems the stock Ex has.
If you want 37" I'd look at using a 4.5" hanger lift with X codes wick will lift your truck aprox 8" over stock and would get you the best ride quality.