For nails and goatheads, I just lined my front tire, 20", with a strip of galvanized flashing, much more puncture resistant than aluminum. No problem at all. As it will not conform to the shape of the tire like aluminum, has to be trimmed to a narrower width. This was overkill for me, but I wanted to make sure galvanized could be worked easily. It can.
I figure my tires are 10x more puncture resistant with the metal stripping and am 99% confident that this is a practical way to stop sharpies. Miles will tell.
Not for racing dudes, gram weenies, ppl who just like to fix flats, or those super sensitive to the ride characteristics of their tires. The metal liners seem to make my tires 'livelier'. I like that. They would likely make for a rougher ride, especially on an aluminum frame. My TE is steel.
We all know that kevlar tires/commercial inserts will not stop sharpies. Would never have resorted to this crazy project otherwise.