I've only ever had one tire that needed booting so I just tossed it and got a new one once safely home.

As for patching such tires two options given so far are for a bit of plastic bottle and some gasket material. And both suggested superglue.

First off by it's nature a tire wants and needs to flex. Adding a fabric boot bonded in place with a flexable glue would stiffen the tire in that area to some extent but the patch would at least be somewhat flexible in all directions. This would include the usual bending as well as being at least a little strechable in the two flat directions. Some patches of the carcase or backing tape from an old sew up tire would have these good properties.

Plastic bottle material and gasket material will bend but they are totally rigid when it comes to being deformable in the flat directions. So the tire is not going to flex in a natural manner in those directions. So while you guys managed with these materials for the cuts you've patched so far I'd suggest that they are not the best material for a permanent boot in most cases.

On top of that superglue is quite brittle when cured. So using it on large areas is going to cause it to fail at multiple points as the glue cracks due to flexing of the tire with each revolution. Over time the bond is going to reduce and finally fail. ShooGoo, contact cement or even silicone RTV sealant would be a better option for glueing any sort of boot into place because they all will flex without compromising the bond strength. But really the glue is only there to hold the boot in position. The fibers do the work. So that's likely why superglue is working since it's just a positioning holder. But still, I'd rather use contact cement or some other flexible glue. And such a glue could be smeared on over the edges to feather them and give the tube less of an edge to worry about.