You need to identify your starting point to determine your options.  

Let me know if you need some good options here; we work with quality accountants all around the country.   

If they don't - then it's optional.  

However, those two options are too pricey for me.

Most tax software has an option to specify that rental income is non-passive, and that's how you do it.

I might do a deal where I purchased the property and provided the “buyer” worth an option to buy for the period of the loan with monthly rent” payments equal to the interest payments on the would be note.  

Are there options for assuming the existing mortgage and financing the remaining balance with another mortgage?

Many of the property managers talk to each other and compare notes and share marketing ideas and 'run comps' on each other.The other option would be the 'enemy method' to search for similar size home within your community and others close by with similar amenities and scour their calendars. 

The art is to increase the rent without running off GOOD tenants (very important, if the tenants aren't ideal tenants then non-renewing becomes the default option).

Current lien holder is going to be pretty much your only option.