This causes at least a second trip charge from us, resulting in more expense for the owner for something that could be easily diagnosed and repaired with parts we stock on the service van. 

", ooohhh-aaahhh that's worth $1k easily right there right.... 

Like going up and down the pitch over a 2 car garage could easily use a tube by itself, for instance.  

Any sort of ACH, check, credit or debit transaction can be reversed fairly easily.

In order to foreclose in a judicial state it must go through the courts and you can easily file a response to the complaint showing the lien is not valid.In non judicial states it would be the same thing, you could respond to the trustee saying lien is not valid and they would have to provide proof of the original note you signed and notarized as well as the recorded deed of trust. 

Some things that might be a concern:1) Obviously have to make sure things are all permitted first2) I don't want the room to "feel" like an addition, so flooring has to be same level/standardized with the rest of the house3) Unlike the rest of the house that has an identically-shaped 2200sqft basement underneath, this added space will not have a basement directly underneath it -- I'm not sure if this poses major cons for some reason that I'm not aware of4) Especially given the lack of basement underneath, I have to make sure that the HVAC can still somehow be piped into this room#2 and #3 are probably my biggest concerns (#1 and #4 I can find out relatively easily)Any tips/thoughts or other experience would be greatly appreciated. 

Again, depends on the market, and many other factors, but it's a market large enough that, if you make the right moves and work with the right consultant, you can easily win at as long as we don't have an entire market collapse. 

I look at what they do which is unsecured short term financing to companies out of money - so that could easily be 40% or 0%.

It seems that rent/value is favorable and easily meets the 1% rule.

It is better to create a separate bank account just for your rental activities.The reason is that it will be easier for you to recognize what is income / expenses more easily.