Mostly, the confederate flag thing is it's "remembering great grandpa" for most of the south. In a time where nearly everyone was racist to some degree (much more so that now), the racist flag argument is invalid. They were neither more racist or less racist than the north at the time. Anyway, I'm tired of the mental midgets having the day. If you are seriously miffed about a flag you need to get a head check.
KKK's views on Hitler are largely revisionist, and pretty inconsequential. Hitler wasn't really a bigot or racist and like most cults of personality you need a demon to scare the locals and he just picked greedy Jewish bankers and other undesirables. It mostly gave him grounds to seize money to fill up the war chest, so don't think it goes too deep.
Most of the white power groups are what as known as "alt-right" which is hardly representative of the bulk of right-wing views. Most of the right wing proper rejects racism, or discrimination of any kind. The right wing doesn't embrace the totalitarianism that would be required to make a new Hitler out of Trump, so invalid argument. Anyway, the right-wing in our country is pro-gun rights and this is about the first thing Nazi Germany would prevent. The ideological separation couldn't be larger.
All political movements have their warts, and if we want to get into it is easy to find them on the left-wing as well. Left-wing movements tend to gravitate people toward laziness, dependency, and equality. Equality was a big thing for Hitler, at least with anyone he cared for - he destroyed the rich, the poor, and made working compulsory. Social programs like free healthcare, and free income were big favorites for him too. With Hitler, you had free vehicles, homes, cash, babysitting, and nearly anything else. You got food with a coupon, and if you ever screwed up you were intimidated by Gestapo to rat on other people. You basically had everything you could want, as long as you were happy to become a Marxist, sell your soul to the devil and ignore all of the people he was killing. (Mentally disabled, old, gay, and anyone that wouldn't work.)