Hey rossrider, have you considered going without the tensioner? I avoid them if I have clearance and use a spring loaded tensioner on the pedal chain if needed, as shown in the photo. These items are available on ebay or you can modify an old derailleur. Eliminating it would save the worry of getting it into the spokes. When I have no choice but to use a tensioner, I drill a 3/16'' hole through the outside right into the frame and install a stainless pop rivet to keep it from twisting.
Very nice looking bike. You won't have any trouble getting looks. The bike either.