You could use a 60 degree with a bearind and use something to protect the surface. If the plastic came with a coating you could leave it on.
You could have got it for $26 and free shipping. Now that's a steal. ;<)Alright I got my answer. Its called a Amana Bevel Rail Cutter. I just bought one. These are the rarest bits and I picked one up at a steal for $35. Now I can see exactly what Im doing and keep the face and surface of my soft smooth plastic material nice and clean. I couldn't find these online or anywhere else in the world. Thank God the guy down the road actually had one. Wow, thats a blessing from the Lord. Here's what it looks like for that future someone coming along with my same question.