People use the "complete circle" of sonotube for subs, which being a complete circle is strong.
My idea might not be suitable for enclosures likely to have higher internal air pressure, ie to play at higher volumes, to play deeper bass and/ or especailly totally sealed boxes.
To reduce internal standing waves but keep construction simple, the back and/ or sides of boxes be formed from a section of sonotube, ie maybe a quarter or a half of the circle.
An advantage of sonotube is that it’s light, so stored energy will be low. What I don’t know is how rigid it’d be. If two layers were glued to each other, it’d be a lot stiffer, and still very light.
As you go up the scale of sonotube diameters, they become a little thicker. As a guide, the local brand here in 400 mm (16”) diameter is 6.4 mm (0.25”) thick.
If the enclosure were to be braced back to front, for strength you’d probably want to face the curve “convex in”, etc
I think it might be rigid enough for small medium volume enclosures: bookshelfs, “monitors”, mids, full rangers etc. Any knowledge of the stiffness of curved cardboard; for which applications the rigidity would be enough?
Maybe it could be made stiffer by eg 'painting' with a two part epoxy . .
How big a problem are internal standing waves, anyhow?