I'm sure the bearings would hold up but the bushings are much cheaper and they also don't have to be precision fit like a bearing would. Actually, I had another idea using pillow block bearings but at a dollar and change per bushing it was a no brainer.
You're drawing looks good to me. As far as adjustment goes, I'd rather have too much than not enough. Mine opens up just enough. I haven't remeasured it or recalculated where I went wrong yet, and may not if the crush is good, but I would have like more adjustment in mine.