A tongue & Cheek plan to open the government but it just might work.
We need a unit of measurement that sounds impressive but is quite small. Micometers could work.(there are 1,000 Micrometers in a Milameter) Democrats need to go to Republicans and Trump and tell them that they will build a wall in Micrometers that is equal to Trump's "wealth." Democrats could then stipulate to Trump's wealth being 10 billion dollars. A ten billion micrometer wall is equal to 6.2 miles. With a bit of negotiation we could get Mexico to pay for a wall that small.
Trump would get what he wants. He gets to have a wet dream because people realize how "wealthy" he is. Democrats get to re-open the government for a tiny wall. Republican Senators get to escape this logjam and Trump will have "kept his campaign promises."
For this plan to work we are counting on Trump and the Republicans to be lazy and stupid. Like I said, it just might work.