You can get a little bit with nail on glides. There are adjustable (screw in) glides, but for these you need a threaded insert and I think the torque would quickly self destruct a glide on a 1" extension.

Another option is to add a seat pad, if you have a chair that would accommodate them.

Thanks very much for your very complete answer. I think we are going to have to find other chairs.

Best wishes.

Andrea