The difficulty in distinguishing these interpretations is that economic nationalism, and particularly opposition to immigration, could be a disguised form of racial and ethnic prejudice. Although surveys show a substantial decline in straightforward expressions of prejudice, many social scientists say that the underlying attitude is still there--people just don't reveal it as directly. In effect, saying that you're against "illegal immigration" is an acceptable way of indicating that you're against non-whites.
A 2011 survey by the Public Religion Research Institute included a number of questions on immigration which shed some light on the issue. One asked people if they agreed or disagreed that "We should make a serious effort to deport all illegal immigrants back to their home countries." 53% said that they completely or mostly agreed. It also asked how well various statements described immigrants coming to the United States today. 85% said that the "they are hardworking" described them very well or somewhat well, and 79% said that "they have strong family values" described them very well or somewhat well. Opinion was less favorable on two other qualities: 45% said "they make an effort to learn English" described most immigrants very well or somewhat well and 71% said that "they mostly keep to themselves" described them very well or somewhat well. Still, the comparison shows that hard-line views on illegal immigration don't necessarily reflect negative views of immigrants.
You can also look at support for deportation among different groups. It was highest among non-Hispanic whites (56%), but not that much lower among blacks (42%), Asian-Americans (46%), people of mixed race (56%), and "other" (47%). Even among Hispanics, there was significant support (24%).
I think these results count against the idea that a call for general deportation of illegal immigrants is primarily a coded appeal to racial prejudice. They also raise a question of why Trump is the only candidate who advocates (at least so far) a fairly popular position. The main reason is probably that people who have been involved in policy-making regard it as totally impractical--it's not just that it would involve enormous numbers of people, but many families include minor children who are citizens, it would complicate foreign relations, have negative effects on the economy...... Plus there would undoubtedly be many sympathetic individual cases--people who had been in the United States for most of their lives, were well-liked by their neighbors, were to ill to travel safely, etc. As a result, a policy of mass deportation might not remain popular if it were implemented. As an outsider, Trump isn't restrained by these kind of considerations.
So I'd continue to put Trump closer to Perot than to Wallace. Or maybe I should say "Trump supporters"--Trump the man is one of a kind, as he would be the first to tell you.
[Source: Roper Center for Public Opinion Research]