I think this is a real hurdle for some people, and may explain why wholesaling tends to attract some shady characters (Please don't misread that. 

I knew the size, current rents, off street parking with garage and older character were what I was looking for.

People love hardwoods and if they are clean and smooth they are very forgiving about any "character flaws" such as old water stains or cigarette burns.

We try to maintain the character of the home as best we can.

Rejection reveals your character.""

For me I will very likely hold all my rental properties indefinitely and have them ultimately pass through my estate so all taxable gain (attributable to both the price appreciation and depreciation taken) will be wiped out so an IRA would only be a detriment for me. 

One thing to note is the 21% tax applies on all C Corp profits, whereas, the UBTI tax only applies on a percentage of the SDIRA income attributed to the debt financed income. 

Quaint, cozy, charming, full of character, anything except small.

Resilience that further builds character.

So.... 1/2 the expenses of the duplex are deductible... ( or you depreciate them depending on what they are...) and any expenses directly attributable to the rented side come off the income ... it doesn't depend on the amount of rent as much as the total after you subtract the expenses from the rent.