I'd suggest using more than just a couple of layers of Tru-Oil over the transfer (and I'd do the whole headstock face, not just the transfer). The layers are very thin and unless you put a lot of layers on, the transfer will stand proud of the headstock face. And when sanding (or polishing) that back, the edges get extra pressure on them, so its very easy to break through to the transfer - even just when using polish and a rag.