Thanks for the replies. I'm going to be feeling my way on this one. The ability to drop the RPM with a different size tire sounds attractive. I'm sure that it's gonna be a gas hog with this two seater hack on it.
Nice looking rig.
There is also a forum here specifically for Trikes, Trailers and Sidecars. It may be a sub forum of the Technical Forum. I'm sure you will find more people who share the same issues and concerns as you on that one.