On this issue, I think we certainly agree on most points. I’ve written a quick reply at The Tenth Amendment Center with a few responses to the points you’ve made, for example:

In my view, a better view is that amendments are pointless, as the state is construing its own limits. (See on this Hoppe and de Jasay.)

That’s actually the argument that I was at least attempting to make in the article – that nullification – mass civil disobedience to the central state, with support from the individual state governments and local governments – is a far better strategy than trying to reform the federal government through amendments (or any other way, for that matter)

I hadn’t considered any of the amendment proposals you’ve mentioned here. While I doubt that I’ll find any interest in trying to change D.C. and would prefer to resist it – if anyone asks what I consider a good constitutional amendment, I’ll certainly be referring back to your suggestions!