I have used 1/32 "catering grade" card for years now to simulate plating. I have always applied the plates to the plug rather than the mould or the hull. One or two good reasons for this;
1. You do not need to be too precise with the fit of the planking on the plug...the plates will cover the gaps.
2. Much easier to get reasonably scale rivet marks on card than on anything other than lithoplate. As I mentioned ages ago on another but similar thread, I make my rivets "in reverse" (i.e. indented for the final hull) as, really, the human eye does not really differentiate between "in" and "out" at this scale..remembering that a rivet head is only about 1" in diameter. Also, if the final hull needs rubbing down you do not lose the rivet marks..not to mention that the marks are "sharper" this way.
3. Using card plates on the plug protects the mould during the removal process...if the plates come off and stick to the mould they are easily peeled or soaked off
4. If you make a mistake, card is easily and cheaply replaced...easily cut to shape and (with a bit of care) reasonably easy to mould around such stuff as prop bosses etc.
I use the "catering grade" card because of its high gloss finish on one side (outboard) and a nice "rough" finish on the other that sticks nicely to whatever the plug is made from. (I have banged on about the advantages of double-sided tape too often to go into it again!).
At 1/32 scale it is quite easy to make the lines of rivets in 1,2,3 or even quadruple rows...as they were, but you need either a shell expansion drawing or riveting data to get it right. If you want more guff on this drop me a PM and I'll send you some drawings. BY.