Few, if any, toilets set tight against the wall. For example, both of my bathrooms have exactly 12" rough-ins. Of course I have toilets listed as 12" rough-in toilets, but both of them have about 2" between the wall and the tank. You can always put a toilet on a flange that is set greater than the rough-in size listed for a toilet, it's when you want to put a toilet on a rough-in that is less than the toilet's listed size. To my knowledge, toilets from all manufacturers are this way. There is certainly nothing wrong with a 7/8" space behind your toilet.