I think this question is probably too complex for me to feel comfortable voting for one of the three options above. UKIP undoubtedly owe their status to their unambiguous support for withdrawal. That was what motivated people who knew very little about them to vote them into the European Parliament, which is what first made them prominent. But the UK is a special case. In other places, I'd say that, whilst scepticism of the EU can be an electoral asset, support for outright withdrawal can weigh a party down. This is the case for the FN, FPO and PVV, and I know that the first two at least have been looking to tone down their rhetoric in those areas recently to appeal to the electorate on the basis of identity based issues instead.
I'd say parties like PiS actually practice a form of soft euroscepticism, without outright support for withdrawal. I think that would likely be the more successful route for far right parties to pursue in most countries, with the exception of the UK, of course.
But isn't Socialism For White People/Nazism For Brown People the basic policy of groups like the Front National in France and the UKIP in Britain(with their pleas to spend more on national health)? And they're euroskeptic in OTL, so I'm not sure you need to make any changes to their European position to get them into SFWP/NFBP mode.
The FN (at least under the current Le Pen) is genuinely committed to economic interventionism, provided it is to protect the right people. Though UKIP gets the backing of economically interventionist, socially conservative types (polling has actually put their voters as more left wing than Labour's on some issues) their leaders are instinctive Thatcherites, and strongly pro free-trade, in contrast with Le Pen and Trump. But they are a socially conservative populist party first and foremost, so they are willing to sacrifice aspects of economic policy for more votes. That doesn't change the fact that many of their most prominent figures have called for the NHS to be privatised at one stage or another, with its general secretary comparing it to Hitlers bunker at one stage.