In that case, you’d typically need to file a legal challenge, which could involve going to court and showing that the restriction is unnecessary or unreasonable.The best advice I can give would be to consult a real estate attorney to understand your specific situation and options.

It depends on the rental income, what you plan on putting down (20-25% is typical, 15% or 25% is required for conventional depending on # of units) For your owner occupied deal, you should be able to use a portion of the rental income to qualify and help offset your DTI a bit. 

.: I would go HELOC for sure that would be best as others were saying the lower cost for the money changes between paying a higher rate for a personal line and typically personal lines they want a higher monthly charge as well independent from the interest rate.  

There are other ways to determine rental amounts like researching in zillow and/or rentometer, which I typically reference.

We go to our property typically 2-3 times a year.

The typical 2-4 unit I represent buyers on we are able to increase rents 40-100% especially in gentrified areas.

I don't think the typical sub-to deal would lead to equity skimming because they are likely close to foreclosure and there isn't enough time to rent the unit back out and make money allowing the unit to go to foreclosure.

@Ezra Avery you might want to read below to understand Classes of Property/Tenants.Property Class will typically dictate the Class of tenant you get, which greatly IMPACTS rental income stability and property maintenance/damage by tenants.If you apply Class A assumptions to a Class B or C purchase, your expectations won’t be met and it may be a financial disaster.If you buy/renovate a property in Class D area to Class A standards, what quality of tenant will you get?

As a new fix and flip investor lenders will typically want to see 20% down payment and will be able to fund 20% of the rehab budget (80% LTC). 

Also, if you buy using a hard money lender or cash, Zach Starnes can do re-fi's off the appraised value shorter than the typical 6mos and then you might not need any money down if you buy at the right price.