What thickness have you found is the best to work with for coppering the bottom?
Not sure of the thickness measurement but I use the standard copper tape used primarily in the stained glass hobby. There are many choices in width however…the last model I used copper tape on was the 1/48 scale so I used the 1/4 inch width copper tape. For the smaller scales there is 3/16 inch width and even 1/8 inch width. But for the scales around 1/50 the 1/4 inch width, standard hobby tape, works well.
Don, due to the difficulty in obtaining standard copper tapes in correct measurements, I have ordering plates made by photo etching. The measurements I found, based on Museums and J. Boudriot books for 1:48 scale ( France) are : lenght 24.4mm. , width 7.6mm, thickness 0.10mm, diameter of nail heads 0.10mm.