This property is pretty far off from the 1% rule.

Using the 50% rule for expenses, I'm seeing it'd bring ~400/month in cashflow once I rent out Unit E. 

You may be able to get a HELOC that gets you up to 90% LTV, but your cash flow needs to account for the second mortgage payment.Here's a blog article with some thoughts on general rules for quick calculations:https://www.biggerpockets.com/blog/2015/09/02/real...2.

If you follow the two rules above you pay no tax on gain or depreciation recapture. 

@Christa S Rickard  I have some multi families, and in general the 50% rule is pretty solid. 

I guess i'm wondering if you guys use some kind of rule for the age of the building if you're planning on holding it long term. 100 years or less?

The SEC is a significant enforcement agency and you want to be on the right side of the law.Make sure you know the rules around contacting accredited and non-accredited investors, rule 506(B) and 506(C), and multiple other solicitation rules.

They're just products of the individual banks that offer them, so each lender can make up their own rules. 

They are in rare form this year, really trying to screw residents out of every last penny they can.They are using comps from early 2018 even though their own rules say the effective date is Jan 1st 2019.I showed them comps from November through January of bigger houses (+400-600 sq. ft.) in my neighborhood selling for less ($20-$30K).

In case you didn't see the recent story about Airbnb regulations and limitations from the City of Louisville... https://www.wdrb.com/in-depth/proposed--foot-rule-aims-to-limit-airbnb-homes-in/article_26a7b458-5c74-11e9-a24f-272568002667.html