If you have a wide mouth that will fit a 2" or even a 1" power sanding disc that would work for the bottom. You may need a extension to reach it. Normally I make sure the inside is sanded before I remove it to finish the outside bottom. I sand with sheets as far as my finger will reach then use a long
forceps that has sandpaper wrapped around steel wool. Most generally I only go to about 150 (100...