Awful idea.
For a mall cruiser it may not matter though.
Do you mean it is a awful idea NOT to have a full size spare on the CT? I agree completely.
In the render below you can see the rear tailgate mounting option for full size spares that will require a custom rear bumper with swing out arms (not shown) and in the reflection on the ground you can see the MS motor and a underside mounted wheel/rim that gets close to the rear bumper edge and diff housing because of it's diameter. Tyre size is scaled to dimensions, just has a different more off road wheel/tyre combo (that I din't have to draw from scratch!) There is a it of vertical height in that under bed cavity to juggle things around still. Definitely possible.