I was planning on building the home in the traditional stick built style in my budget but am wondering if doing prefab may save some money/have other benefits.

It’s not a binary on/off choice.

So they really had no choice IMHO....Welcome to the landlord world I guess.....makes ya wonder why we do this sometimes, huh?

With it being a difficult property for an investor to find traditional financing for, how would I go about assigning a realistic valuation for the property if we were to entertain a sale?

These lenders often have more flexibility with underwriting and may not require traditional income documentation.

While you can't take forever and a day, because a desirable candidate has choices, deciding too quickly can be disasterous.

There are more details here if interested.I will not tell anyone to do or not to, that is a choice that you will have to make and also it is a choice to work it or not, like any system.

While the traditional approach involves buying a multi family property, living in one unit and renting out the other - with rising prices and interest rates; others have considered renting out bedrooms as unit spaces. 

I've seen some pretty killer terms for foreign national Canadian loans from RBC bank, if they can meet traditional income qualifications.

To invest in Section 8 housing, look at areas such as Cleveland, Columbus, Cincinnati, and Dayton, choose safe neighborhoods, study Section 8 standards, analyze property types, and explore financing choices.