ABSOLUTELY you can back in minimotards. I find it very easy on dirt but was having a bit of difficulty on my first try on the tarmac last Saturday on someone else's bike. Very different gear ratios to mine and just couldn't back it in without sacrificing too much speed or not being in the right gear to power out of the corners. He was also running very different tyres which had a completely different feel/feedback to mine. Total lack of front brakes, and I'm serious when I say they did NOTHING. So couldn't get as much weight off the rear tyre. Also binning a bike when it's not yours is an issue, full leathers or not

As for riding style I love to drag knee but I find that foot out/body more upright makes it easier to throw the bike into a corner. I'm also yet to see any videos of minimotards sliding into corners but then again there really aren't many decent minimotard videos.