I can't really answer the core question of where the APR canards should go. I can tell you about the canards I have and how they were set.
I bought some Reverie carbon canards and was disappointed with the fit to the body as there was no possible way I could get the to sit flush with the body work. I know I could have drilled holes, tightened down the bolts well and squished it all together but felt that method left much to be desired.
So I returned the parts I bought and then started messing with making my own. I made a set out of heavy cardboard and covered them with duct tape and taped them to the car. I then hooked a Go-Pro to the front of the car and pointed it at some sections of string I placed above and below my cardboard canard. I learned a good bit doing this and changed the amount of curve and angle of attack of the canard until I had good attached flow around the part.
I then used the cardboard part as a pattern for some parts that I made out of 1/8" ABS sheet. I cut and heat-curved the sheet and then mounted it to the clam using sections of aluminum angle and special 3M autobody double sticky tape.
I do a lot of solo events and wanted to be able to whack a cone at speed and not have the clam damaged by bolts pulling through so I used the tape. I've had the car far over 100 mph many times and they've never come loose.
I've attached some photos of my set up.
If I had the APR canards I'd tape them to the car and see what the airflow is like with some strings. If they are just bolted on without any testing then you'll never know if they help or hurt you.............and very small changes have large effects in airflow.
I used the same strings and a Go-Pro set up to test my rear wing angle setting and to check airflow around the front splitter. I can tell you the package really has the car stuck to the flow and predictable at speed - a very nice change from the car without all the stuff bolted to it.