I bought this, some catches to it, though
www.airplanecolor.com
The program is called Model Airplane Colour Design
This is for RC models, but it's inexpensive, and has a model for an RV-8.
I bought the software recently.
What it does not do, that I need, is model the curvature of the fuselage.
It's great for upper and lower wings and horizontal stabilizer, and for the side view of the fuselage. The upper and lower edges of the projected fuselage are bled together when the 3D views are presented.
If you are looking at projecting an image onto the curved surfaces, this will not be adequate.
However, for a lot of paint schemes, this thing would be very good.
Excellent viewing tools, and a free demo (not an rv-8). The program also allows side-by-side comparison of two models.
Again, if you have some detail to put on the top, or on the bottom of the fuselage, this tool is not going to do well.
I'm looking back at the RV-8 model for Microsoft Flight Simulator next, unless someone else has a better idea here.