Like anything else I guess it depends on how many lots relative to the overall size, how good the deal is otherwise, and the general characteristics of the park/lot owners.  

Assuming your bathroom is an average size (5' x 8') the additional cost of replacing maybe 4 sheets of drywall versus the labor intensive method of patching, floating and sanding the existing walls, and hoping you get a uniform finish, is a no brainer.

After reviewing many medium-sized cities, mostly near my hometown in Southern Michigan, I discovered Fort Wayne.  

Next door house 4/2 same size asking $385k.Bought a 3/2 condo in Stockton in 2014 at $70k.

Depends ont he size of the park that that figure should get you close. 

Aside from the overall high price levels which will probably be insurmountable regardless, there seems to be a very narrow market for the size area we're looking for.

Ask the listing agent or owner they will know.It could also mean though that depending on lot size that you would need  to dig a well and put in septic.  

My long-term goal, besides building up a portfolio of rentals, is to establish a small to medium size property management company, where my wife and I can concentrate on giving exceptional service and individualized attention to our customers.

What size is good for 300k properties that would make a new buyer happy?

From what I've seen Oregon and Eastern Washington seem to have decent sized investor communities.