I completely agree with @Ashish Acharya's points about the cost-effectiveness of a HELOC and the potential credit implications if it’s secured by your primary residence.

The cost of entry is lower.   

Paying a bit more might be justified if the pro forma income is very achievable, but $360,000 seems too high unless renovations are already complete.Factor in the costs and timeline for completing renovations for the studio and the fifth park-owned home.

Can try to reposition to Class B, but neighborhood may impede these efforts.Vacancy Est: Historically 10%, but 15-20% should be used to also cover tenant nonpayment, eviction costs & damages.Tenant Pool: majority will have FICO scores of 560-620 (approaching 22% probability of default), many blemishes, but should have no evictions in last 2 years.

Here's a big "math" you overlooked for quite a few years.Right now $388k in equity, minus (let's go all out) $100k in closing costs, gets you a walk away of $288k in equity.Use that $288k as a 20% DP, and you should have $1.44M in property value,...not $415k. 

Perhaps if your partner was a general contractor or handyman type there may be some merit there to reduce costs / increase profitability.If your partner enjoys deal sourcing, a better move might be for him to become an agent - so he could legally collect commissions from finding deals and managing properties for multiple people. 

I don't expect to know everything by then, but I hope to develop a basic strategy that prevents me from making the most common and costly mistakes that a newbie can make.

If a prop is 250k and you can refi at 70% LTV you want to get it at 175k minus rehab costs.

I'm not satisfied with not filing the rental in an LLC simply because it's more simple and might cost me an additional filing fee .

A good landlord understands that vacancies & Rent-Ready costs will destroy your cashflow and profits.