You don't want to be on the bare wood. You could do it over your first or 2nd coat of epoxy or just varnish over it.

If there's a local place in your area that makes them, they will give you a reject or scrap to try. The substrate on the decals gets changed all the time and there are also many suppliers to the industry for various surfaces and conditions. (Food industry, freeze tolerant, heat tolerant, indoor use, outdoor etc.) So, you would have to experiment with one from the place that you would use.