As loathsome as Trump is, there are legitimate reasons why lower income workers would favor him. While I disagree with protectionist trade policies I can see why it would be appealing to a guy working in a slowly shrinking factory. While I disagree with stricter immigration policies, particularly the cruelty which Trump endorses, I can see why a roofer might find it appealing.
But, while that may demonstrate a political advantage of courting these voters with these policies, I don't think it is a viable platform, long term, for the Republican Party. It's one thing push a steel tariff. It's another thing to deal with the consequences - higher construction costs, retaliation by other countries against our ag products, etc.. Long term, I don't see the GOP sticking with a protectionist trade policy. I think they are also going to get pushed by big business on immigration. If the low-income workers dream comes true - if wages really increased because of stricter immigration - it means that corporations are paying more. The Republicans have not been very successful in maintaining a big tent, and it would be really difficult for the GOP to cater to both the low income workers and the wealthy who would be paying them more. And we know who funds the Party.
Assuming Trump loses, and I believe he will, and assuming the GOP loses ground in the House, the Senate, and state governments, and I think they will, the Trump model will proven to be a failure. Certainly both parties will work to court the Trump voter. But these are not well thought out policies and they do not benefit a majority of people in the country. It's not just bad policies; it's bad politics.