Hello Camel,
You will need to install an auxiliary outboard bracket on your transom, very easy to install.
Here is a link of a few brackets, they are available at most marine parts stores.
They run about $150--$300
http://www.cabelas.com/p-0000921.shtml
Scott
No you dont need a robust bracket for a trolling motor, just a simple adjustable to accommodate the curve in your transom.
As the light weight of the trolling motor the bracket would be screwed into the glass.
The larger brackets are through bolted.
Marine Mechanic
26 Years in Marine trade/ marine college/onan/RV appliance school