I am not sure what areas you have been searching but you most likely will not find anything in that price range that you can easily flip.

I doubt you can move much past 10 deals a year on the side and you need to do volume in order to become good at what you do, understand all the different submarkets, land, condos, price ranges etc 

I’m looking at MFH but the price range seems to put me in a “bad area” of town and most need a lot of work.

Rents in the area for similar units range from $1000-$1200/mo.

Then your choices will be to find alternate lending sources as you've mentioned or finding properties in the range your lenders say.

Just from a pure market standpoint, your are going to be hard pressed to find worthwhile duplex/single family homes in your price range from Greater Worcester -> East Mass.

I'm looking to perhaps purchase a new construction SFR (4-5 BR) within the 350-550k range in Charlotte.

While I would be cautious here given how things developed, I would think that if you have done all of the relevant background research on the original applicant and he met your criteria (3x the rent plus the stuff I mentioned above - you'll need standards so you can treat everybody the same) then it wouldn't matter if he added someone else as his income and credibility should sufficiently cover.

I generally recommend the following suburbs of Baltimore for solid rentership: Columbia, Glen Burnie, Towson.So in summary, if you found a househack in the range of 200-350K, I'd expect to have 12-17K saved up for an owner-occupied, first-time home ownership structured deal in the surrounding counties of Greater Baltimore. 

The comps in the area are similar but relatively low 700 to 650 range with the occasional 1 mil.