The best way to prevent the tarring of the rightist coalition with the evils of Nazism and other extremism is to take a leading position vis a vis borders, language and culture. Don't leave the hard lines regarding national sovereignty to the extremists. Own the hard line and drive it. One can take such a position without being racist. In fact, the smartest lovers of freedom and human rights understand this. Witness Michelle Malkin among others.
Why not call a spade a spade - admit, "Yes there are out-and-out neo-Nazis and racists out there"; then work out a practical solution that cuts them out of the deal entirely?
And Michelle Malkin, in my opinion, is hardt a smart defender of freedom. I think Linda Chavez has done a far better job - and has actually DONE THINGS (witness her work at Center for Equal Opportunity) on many of racial and cultural issues, although my leanings are more libertarian than hers.