The only options that I see are rent by the room, mid term, short term, or just putting more money down.

Long term building equity. 

Trying to figure out what their pain point is to see if terms might help. 

My goal in the long term is build up enough equity/extra income to retire at 50.

@Nick Pamintuan I would start with understanding what each of the six partners (including yourself) bring in terms of value to the partnership.

My goal is to at least match my current monthly expense of $3k (After all units are rented) while aiming for long-term appreciation.

Though it is a negative cashflow move in the short term, I fully anticipate rental rates to catch up to the expenses in about 3-4 years and break even monthly.

Free attorneys from tenant-support groups are very effective in finding ways to block and delay.PS: for anyone interested in supporting our landlord legislative efforts please join the Rental Property Association of Wisconsin RPAWI.org which is a Milwaukee-based non-profit.Cashflow in Milwaukee is still possible at current interest rates, but you have to be careful to not "buy cashflow" with a huge capex liability that comes with old buildings! 

Lightstream is the most famous, but the longest term they lend is 7 years.

My investor friend has a lease option on my property to assume my mortgage and property so she can get the terms, while giving me $30,000 over two years for the option to assume my mortgage and property.