I would budget closer to 12-15% of gross on your pro forma because no matter what the PM % is, they will charge by the hour for everything "above and beyond the norm".

My sister and I would like to form a new Family style business in and around Boerne TX.

I would also get some legal advice form a Real Estate attorney and not just an Attorney as to how to proceed. 

I've begun to model out a land acquisition and MF development pro forma for a 7 unit, 8000rsf apartment in San Diego.

In particular as it relates to RE.Is it not true one can form a Property management company to manage their rental and thus be eligible for a Solo 401k?

Conservative pro formas are possible if you are really familiar with the market and costs involved, but too often overestimated.The fastest way to make money in RE is to throw lots of money in it, if that fails, thow more money in!

If you find you work well together, then you can always form a new entity together down the road.

I think you will first need to add a subordination clause and then put together a really good pro-forma operating budget and income statement.

There are so many unforseen variable that can and generally will affect actual performance that, while you can make a good guess, I have never seen one that was on the bottom line.IMO, again, lenders want to see your pro forma as part of your loan package.

Im weary of many of these companies due to their inflated pro forma, and over priced management fees.