Because I do not show large profits in my business and cannot get a traditional loan under 5%

Hey @Pat L. your right, I'm starting to find that it is an entirely different animal as compared to the multifamily value add model that I am used to. 

What expenses are there on manu homes as opposed to more traditional stick houses?

Good for short term bridge to traditional financing. 

My plan has been to start an LLC, and purchase a duplex using traditional financing with 20% down.

A lot of lenders will not allow for this so it certainly needs to go the private route opposed to traditional. 

I don't think it is wise to look at the 5 year appreciation numbers for SD and compare them with cash flow in the midwest.

Traditional wisdom is 1 year minimum.

Comparable sales in the area can be very misleading unless you know the area. 

Based on my current experience with this compared to #1 and #2.There is an advantage to cutting your teeth on something easier up front...that being said I think you can buy bigger and do a Great Job focusing on inspections to cover your back side, and get best of both worlds.