If you have ethical concerns with this method of real estate transaction, then don’t partake in it.  

But if I'm targeting seller-financed sellers, I'm not really targeting distressed sellers.For example: I came across a seller finance deal for a 1.1M 6-unit MF property, but the owner wanted 100k over what I thought was the market value. 

No control over the investment - they decide when to sell the property.

I have over 800 score never carry a balance and 1 mortgage for past 5 years with no other debt.

You have no control over your own property if you allow a new property management company to choose your first tenant when you only have one property.Know the costs of every call, handyman, etc in advance.

Second because they can’t borrow the amount over the property’s appraised value, even for the furniture.

I respect your personal choices, however I can't imagine ever going to somewhere like Montana and making the decision to stay in a hotel over a cabin rental.

Furthermore, what if there is a dispute over parking between the two?

We as a firm have investors working with us who have rental properties all over the US big and small.Finding a real estate-focused tax professional and one who can help with advisory and grow with you would be my suggestion to focus your efforts on finding.

There apparently was a guy that was very active on BP with over 4,000 posts, regarding buying subject to properly, but has either been booted off or canceled his account.