High spill and impact damage area.  

I know many people who work with ITIN numbers as they have work visas and working towards getting permanent residency.

There are tons of emotional and social impacts.

Thus they have negatively impacted their net worth.I disagree with @Jonathan Twombly that this says anything about cash flow vs appreciation.  

This means we are now a full week behind schedule and this is impacting my next trades that I have booked, from windows and fireplace all the way up to the first of the mechanical trades.By now we were supposed to be framing the second floor bedroom walls and preparing the site so the trusses could be delivered and craned up on the roof.

If the markets get better, they can refi to a lower, more permanent financing, if not, they can ride the wave or sell.It's all about your plan and anticipating what might happen so you can mitigate losses and assessing how much risk you are willing to take. 

eventually I’d like to build a permanent primary residence for my family on this land, and convert the first modular home we would rent into an ADU.

But as it bears on REI, upcoming policy decisions in Washington, our state capitols and City Councils can be very impactful to the decisions we make as investors.

So the only way I would use my margin account to prepay some mortgage payments would be only do it with like 20k or 30k at a time, so even if rates did rise, it wouldn't be impacting a massive amount of principle. 

Look at the numbers for each property and do it if it makes sense financially, not based on what you think the impact of the virus will be.