First I thought they were manufactured houses.

Also note that most houses in Seattle are not 2700 SF, and there's a certain economies of scale to consider too. 

I’m not looking to hit a home run on my first deal, but I feel it’s necessary to consider the massive benefits of economies of scale via purchasing multiple doors.My question is: Is it realistic/ reasonable for someone in my position to go after and search for a +/- 10 unit property with help from other investors?

Mike,  First you want to make sure that you are talking modular versus manufactured. 

Seems to me many, if not most newer note people think "commercial" notes typically equate to large-scale corporate property; but small business owners (like a small factory or warehouse) take back notes, too.

As the scale grows, you get access to better managers, contractors, lawyers, vendors, accountants, etc. 

I agree with @Jay Hinrichs, especially as a beginning and without any scale, out-of-state rehabs bring on a lot of risk. 

I also hired professional property management a couple years ago when some of the more intrusive Seattle rules hit,   but again this was a modification of my existing plan which required that anyway so I could keep scaling beyond what I could manage by myself while I still have a full time job.

It takes a lot of work...Best of luck as you scale up in Columbus. 

Economies of scale do work.Be persistent and hustle!