es Fred,I'm for the largest print with margins on a A3 paper.The printer is a Canon 8300.I understand that there are limitations on the driver witch prevents to have equal margins but maybe I just miss something and I was hoping to apply your method for this issue.
Canon would not let me install the driver until I installed a firmware update to your printer, so I used the next best I could find., ipf 6100
As you can see by the screen snap, I have A3 paper and the largest print with equal margins.
16.30 x 11.46 with .12 inch margins all the way around.
I hope this is what you wanted.
In Qimage Page set up (printer driver), I selected Heavyweight Glossy Photo Paper II. (Just wanted a quality paper selection)
Paper size A3; (in driver page setup tab); Paper Source, I selected Manual with 3mm margins.
OK out of the driver, and back to the main screen of Qimage.
From the Print size selection, select FIT TO PAGE, add your image with crop scissors on of course, and there it is.
To check your location on the page, and that you are centered, just go to the Full Page Editor screen and click the LOC tab.
See my screen snap.
Hope this helps.
I have to go out for about 2 hours. (Dr appt) Told you I was very very old!
Should be back by 9:00 am EDT
Fred