@Luis Vaca I don't know much about your family situation, but if you are single and able to sell your primary home I think that is a great solution.

The solution was to install a standared water heater (~40 gal) downstream from the tankless as a holding vessel. 

You know what the solution to that problem is....dont sell in a down market. 

Does anyone know if this is possible at all or have another solution?

Assuming there was no simple typing/scrivener’s error, then making a deal with the neighbor seems like the only solution.....maybe a prescriptive easement.

I think I've worked out a solution.

@Lydia Bolling most of the hard work can be done anywhere you have an internet connection so your lunch hour and after the kids go to bed are perfect times to do research, if you don't have enough time maybe the solution is to narrow the search so that you have less properties to sift through

First, your goals should never include a number of properties...those are the wrong numbers to focus on.Second, holding the property appears to not be a profitable solution. 

Easy solution! 

Hopefully you are able to figure out a decent solution.