Again if I can help these folks in any way I want to not only for them but also for my personal experience and reputation.    

Can anyone suggest a reputable property management company located in the King of Prussia area? 

I loaned $20k to a guy last year I'd never met and didn't bother to record the deed I got because someone I trust said I could trust him (and said he'd pay me back if that guy didn't)  Reputation goes a long way in this biz when you've been at it a while.Anyway, things vary from state to state on doing it, but its essentially just two documents, a note outlining the terms of the loan and a security instrument (security deed, deed of trust) that encumbers the property with the note so you cant sell it without paying them. 

Are there any reputable lenders today allowing 80/20 combined loans?

If you get a reputation for wasting everybody's time, nobody is going to want to work with you.

 @Elizabeth Colegrove  Is it smart to find a bank that does portfolio lending as well but first exhaust the conventional methods, build a reputation then work my way up to the lending managerOrFind any bank that will finance my first deal, try and repeat the process a few times and when I need a portfolio lender just start searching when I cross that bridge.

While I was interested, (not for a profit, however) my instincts told me to be careful and not rush into things as my reputation was at stake if his data or service was questionable. 

If they are well established and have a reputation, you are at less at risk of them losing your reserves.

If you use the weasel clause too many times you will get a reputation in your town as someone who can't close.

I don't believe that a properly worded letter of intent will be a legal issue; it is just a matter of reputation, and basically doing business transparently and honestly.