This is exactly the sort of concerns I was hoping would be raised here about the chainring spacers route. When you say the spacers must fit tightly to the screws, do you mean in terms of the inside diameter of the spacer matching the outside diameter of the bolts?

I had similar thoughts - with spacers, the crankset spider itself would no longer be supporting the chainrings. So it would just be a matter of friction with the chainring touching the spacers, and the spacers touching the spider. Of course, having the bolts really tight would help as it would maximize this friction. But still, I think if this plan goes wrong, this is where the issue will be.

Here's an example of bolts and spacers that I was thinking of using (I wouldn't need the nuts). https://www.ebay.com/itm/184989039679

Interesting that you say this. It's a brand new chain. And the chainring has about 1000-1500 miles on it. I didn't think that was anywhere near long enough to cause significant chainring wear? The old chain didn't have any measurable stretch when I took it off, I just needed a different length chain as I moved these parts from a different frame to this one.