First, if you're not using a service, how much time do you spend with each lead?

I spend in marketing and acquiring motivated sellers. 

To get there, at a minimum you will have to:Repair the 11existing homes x $15k per home = $165kHunt down 7 used homes, transport, set up, make repairs x $25k per home = $175kSell all 18 homes to qualified tenants (you will likely have to carry paper on the homes, which will eventually return the capitalization above, but assume it will take 5 years or more)Repair the park infrastructure, roads, signage, the residence, landscaping, etc (let's assume you will spend at least $50k on this if you are lucky, though it could easily turn into a lot more) The bullet points above will likely take a couple years and it could take double that, depending on how aggressive you are, what the availability of good labor/contractors in Indy, and what kind of demand exists for that location.  

I don't know if there is a defined number of hours you have to work each day but let's just assume you should probably spend at least 4-6 hours per day on "business" items.

Second, typically even if properties are in great shape you still will want to spend some money on repairs, typically one of the better ways to make money in real estate is to find properties that can have value added to them, via hiring contractors to do repairs and improve the property. 

A partner and I spent four years remodeling and turning around that property, spending quite a lot of time on-site.

Give yourself a budget of perhaps two hundred dollars to spend on used books from Amazon.com and other sources.

@Alton Williams I started with about $40K saved up, I spend my first few years Flipping houses, building up the pile then graduated to rentals and continued flipping, I havent done a flip in over a year now, but would if the right one came along. 

I have 2 small kids and I intend to spend their school years with them as much as possible. 

Spend some time studying everything about the market you want to buy in.