There have been R'C models with vacu-formed plastic wing tips, and I'm sure it's not new to control line models with all of the small kit manufacturers there have been over the years. If I were to do it, that is the way I would go, but then you may have some paint adhesion issues, or just try to dope on some tissue strips so you have a good base for paint.
One way or another, you are going to have to carve at least one!!
Type at you later,
Dan McEntee