@willni; good advice on putting a mark on the backing plate - I’ve done this on mine and it is a useful check to make sure the backing plate and pad are rotating correctly.
I have a couple of 3” backing plates and a selection of spot polishing pads that will fit onto my DAS-6 Pro Polisher. Admittedly, even with the 3” backing plate and a spot polishing pad, it’s not possible to machine polish some areas - e.g. the recesses behind the door handles - but most areas of the car can be tackled.
I dare say if I did car detailing for a living then I’d upgrade and invest in something like a Rupees Bigfoot for large panels and a Rupees Mini Bigfoot for the more intricate panels. However, I’m just a detailing hobbyist who machine polishes their car probably once every 18-24 months. With the amount of use my DA gets, the DAS-6 Pro with a selection of small and large backing plates and pads meets my needs.