If it's a defunct, decrepit building, it will offer one heck of a counter-point: this is what past trade policies have wrought. Or, perhaps it's one that has survived and perhaps thrived. The, it could be an example of what Trump promises.
Personally, I think Trump needs to build on his trade positions with how the cost of regulations have increased the cost of employees, causing a lot of the off-shoring. Obamacare is an object example of that, but he has to make it simple -- without scaring people into thinking they will end up with no health insurance.
I also think he should confront the minimum wage debate, and say: raising the minimum wage will simply shut out a lot of young, low-skilled workers from entering the market and getting the experience they need. But, he has to counter that with the expectation that the demand for skilled employees will raise wages for experienced people that are currently working for minimum wage.
I don't know how you make these points for people that can't grasp the law of supply and demand. They don't teach this in school, and economic illiteracy is just one of the reasons it's an uphill battle to reach people that reflexively vote Democrat.
I hope Trump hammers your point throughout the rest of the campaign, but boils it down real simple that it can be repeated by anyone, anywhere and understood by most everyone.
Whatever you regulate more, you get less of it.
Whatever you tax more, you get less of it.
What do democrats excel at? Taxing and regulating every element of the economy at every level.
Essentially a scrap yard, all that's left of the once mighty mill that occupied the site along the river.