On this subject, has anyone seen (or are there any lenders who know) how this would impact your mortgage which assumes your building will be owner occupied?

Don’t forget the tax advantages of depreciation, mortgage interest, property taxes and the impact of your tenant providing the mortgage pay down.  

You should also look to see if the work you are doing will even require a permit, if the work is cosmetic only and / or only impacts a low sf then you may fall outside of what they even want to see.I'd also dig further in to the submittal requirements to confirm that you need to submit hard copies for the work, many jurisdictions have moved to an online submittal system which makes life way easier. tldr; no unless a professional stamp is required and you are ready to spend a lot of time learning.

This has had a tremendous impact on me and I am looking for a way to help.My thought is that someone is going to end up buying that lot and building a new home and likely profiting from it.

This impacts quality of life just as much as cost of living.Don't assume that if you move from SF to Tulsa that big, fat SF salary is moving with you.

But you also have multiple properties that are using leverage so you get the arbitrage of debt and the impact of using leverage to purchase. 

This to me is the most intimidating part of getting into investing because it seems there are so many small mistakes that can be made that have a big impact on the performance of your new property.

Being stuck in a year lease will impact your bottom line, but isn’t necessarily a reason to run away.

So your DTI should not be impacted by the amount available on the line of credit.

Obviously applicants are stronger if they have jobs in industries less likely to be impacted by COVID, but we should not discrinate on source of income.