. $200 per month is a pretty thin profit margin for a duplex, and that "profit" can disappear in a flash. 

These are useful for low-use various building supplies that can be affected by moisture, stuff like drywall tape (especially the composite tapes), fasteners (that weren't sold in the big buckets), various hardware (still in clamshell packaging wherever possible), any sort of rubber or vinyl hose, etc.Larger supplies (rolls of tubing and electrical wire) go in garbage bags.Sheet good like OSB, plywood, cement board, and drywall are a real pain.

Be cautious if your planning on making a second illegal unit, I can't emphasis how much of a pain it is if the city finds out.

Definitely a pain in the hind end for you and will cost you some money. 

But 12% + 15.4% makes for a painful tax pill to swallow.

I had forseen this years ago but I aways thought the pain in the tail of reading meters and billing tenants was too much work vs. charging more rent. 

Every city has pain points and issues.

If you do need to 'disappear', I was once advised to find a friend in a different state.

Now, if you execute a 1031 to defer your taxes on the sale of this property (A), they don't just disappear (yet).

, IF he does not disappear, IF he has skills to match the flip you do.7.