Robert,
Thanks for taking on this project. It looks like it will be a benefit to us all. :-)
Like many others I like the FW 190/FW Ta152 series for CL stunt. There are two good CL FW designs already out there though, so you would not be too original with one of these.
Another plane that fits your specs is the Edge. It is a midwing, making room for your pipe. The 0-0-0 Eng/wing/tail would also make for a good CL set up. Here is their web site with photos, specs, great paint schemes, etc.
http://www.zivko.com/edge/site.htmlThe Extra 300L would be another good choice, but they are very common. The Edge would be unique. I really like the looks of the Extra 300L, I own three of them in 37% scale and they fly great, but one of my favorite planes is my little, pattern size, 25% scale Edge. It flys great, even with it's small OS 1.60. It is very solid, and looks good upright or inverted. I often think it would make a wonderful CL plane.
To my knowledge no one has done a modern Edge in CL, and the scale paint schemes available are way Cooooool. :-)