I figure the three possible outcomes are 1) they both stay2) that she moves out, he stays3) they both move outPossible complication being that he stays, she moves out and he doesn't pay.  

You can establish a good business plan and run a rental property business without an LLC and it will be less complicated for you to do so.

Also let me recommend that if you do go the sump pump route, install it in the dry season as it is my experience that digging a new pit below the water table is ridiculously complicated.

Specifically, I'm looking for somebody with experience in entity setup/creation (I have a slightly complicated financing situation that will need to be managed to fund my REI business).  

For the most part, commercial seems a bit more complicated than flipping an SFR contract like this. 

Hello Maura,As long as your loan is presented and structure properly up front the UW should be able to figure out what you're doing quite quickly.In my opinion 60 - 90 days is unacceptable unless you have a really complicated file or the customer is really slow in getting the Loan Officer what they need.Find an LO that knows what they're doing and you should be able to get this done in less than 30 days 100% of the time. 

I didn't want to complicate the HELOC application, or screw up a new conventional loan app, by trying to do both at once, and the closing time is pretty much the same, so buying with the equity line cash is pretty much a done deal for now. 

(in retrospect it was likely because his commission would have been complicated). 

Pretty easy to get along with, the money showed up at the closing table on time, and the draw process wasn't too complicated.

They're not that complicated...or expensive.