That's the way to go about it, but the decal has to go on to a 'bare metal' background, so the use of white decal sheet as a 'backing' is probably not viable.
I think I would make a single decal, apply it, and then paint-in the 'lost' density etc.
Ink jet decal papers are fairly thin, but the carrier film can still be seen on certain surfaces, and against the 'silver' background, overlayed decals would possibly show the edges, and would probably show even more clear film after aging, as yellowing occurs, not normally as noticeable on a 'coloured' background.
I use decal sheets from a computer papers supplier, which is exactly the same as the material supplied under the 'Bare Metal Foil' and 'Testors' labels, among others,with the same back-printing and packaging, but about a quarter of the price of the stuff re-packaged for those other companies !