Yes you can still use a 7.5" pad with a 5" backing plate. Backing plates are all pretty much designed the same. It's really the strength of the velcro on the pads and the quality of the pads that matter a lot more than the backing plates because that's what is coming into contact with the surface of your car. In your other thread I said that I bought my backing plate from
www.properautocare.com. You can pretty much get them anywhere.