I don't know, but bushings with washers should work.
G'luck
I used 1/16 wall tube for my sticks (22 stick length with 20 inch step spacing). I bought 7/8th OD oak dowel from lowe's and inserted long wise about 2 to 3 inches of dowel in each end (where each step/stand off is), drilled the 1/4 inch hole and bolted them back together. I am 220lbs, used them all season and had zero issues with them.
If I’m understanding this right, are you doing that mainly to reduce the chance of damage from over tightening the bolt? It seems the bushings would be more to alleviate the downward force from the bolt against the thin wall, and I don’t see how the dowels would help that? Plus it seems you’d lose the marginal weight savings of the thinner wall by adding those.