DK,
The channel is only about 1/2" below the motor mount. Granted, the header might have to be bent a little, but I'm thinking the header and can could be made to lay into the channel.

The UCD is now ready to test fly, hopefully tomorrow. The ST 90 has a normal muffler for now. No cowl since I didn't want to cut it up before giving the MCP a chance. No wheel pants, and the tail wheel was replaced with a skid since we fly off of grass. The canopy will be left off for the first few flights just to see how it affects the knife edge tuck once it's installed.

The only real deviation was mounting the rudder servo on the bottom of the fuselage to use a pull-pull on the rudder. The elevator pushrods are 2-56, but the aileron pushrods are 4-40. After reading this thread, the battery and receiver are in the rear of the radio compartment, which put the CG at 5.5 back from the leading edge.

With five Futaba S-131 servos, a S-148 on the throttle, and a five cell 700 mah battery, the dry weight is 7 lbs, 2 oz. Replacing the stock muffler with a MCP just might put the UCD under 7 pounds......which would be great!

Now all that's left to do is stop it from raining tomorrow.