Advice on townhouse transfer from family member. (northern virginia)

[Justin Sherman]

Hello, I'm looking for options/opinions/ideas on how to basically take over ownership of a retiring family members townhouse in northern virginia, for the purposes of renting it out long term.

You probably ask, "Why dont they just put it in a trust and name you the beneficiary?"
I don't want this to be a charity case , so I'm trying to figure out a way to "purchase" or "finance" the house without actually going through the traditional home buying process.  I.e. i want this person to get their equity out of the home (provided by me) without having the tax headache and drawn out process of a sale etc.. 

Folks local to the DMV area know how precious of a gift it is be able to have a lead on a nice townhouse , to not have to compete with other buyers and drive the house price up, so that is the advantage i have here, and i consider that a gift enough , without directly inheriting the house.

They arent hurting for the money, so im trying to think of creative or long term ideas, some things that come to mind:
1.) lump sum up front (maybe using irs gift limits?) and then split rent 50/50 until a limit is reached, once limit is reached i take over deed
2. ) somehow seller financing with a generous term

Please let me know if i am overthinking or getting too whacky with this, I'm just curious what others would do.

Some relevant details:
1/2 way through a 15 year mortgage
located in northern va
will be put in a trust regardless for asset protection
zillow estimate is 690,000


TLDR
want to take over family house to rent it out long term, but dont want it completely gifted to me, how can make sure owner gets paid over time?