Mounting is no issue at all. Most tire shops can do the rears.
The trick is having the machine that can balance them. I went to 6 different places and none would work. They all had good coats equip. In desperation I stopped by Costco, they had the latest high tech Coats machine. They would not mount the tires because I did not buy from them, but the service manager after hearing my story balanced them for free. He resfused payment or a tip. It was close to lunch so I bought the whole crew In-N-Out. I am a long time Costco member. Kudos to Costco.
The issue you will find with most balancers is that when mounted the inside offset of the rim comes very close to the machine. This give the machine an error message and it will not proceed. They all had spacers that were for large hubs, we tried them all and nothing would mount up true.
I searched high and low and could not find anyone with a roadforce balancer that was not a Porsche dealer, and they had no interest in helping me out. :thumbsdow ....Maybe they are still pissed about the GT kickin' some Porsche bootie in the mag tests.
The Costco balance has been tested to 170mph with no vibration whatsoever. The fronts were balanced on a normal coats machine at America's Tire that was fairly new, no issues with the fronts at that speed either.