I have been investing mainly in trust deeds but like you got connected with Dave and just recently ended up investing in his fund, my primary reason was for diversification and because it is passive. 

Purchase price: $325,000 Cash invested: $150,000 This was our first primary home and was converted to rental after living in it for 10 years.

In my area this is the primary permit that is required that is virtually never got. 

Would the buyers/borrowers be purchasing with the intent of putting a mobile home on the property and making it their primary residence?

As an investor your ratios won't look good to the traditional lenders.

There are still a few that will give you a loan but the traditional 90% of purchase price and 100% of rehab might not be possible without an exception.

But the manager's unit is really a 3000 sqft / 4 br / 2.5 ba SFR, and we live there as our primary residence. 

Hello Ralph,Yes you can used a HELOC from another property as a down payment for a new one, then get traditional financing on the remaining 100K. 

For the ballon payment I would plan to refinance into a traditional 30 year loan.

I completely renovated the primary and guest bathrooms.