This is the bank I worked for, and we were constantly kicking contractors off the program for not ensuring the people creating the loan were actually authorized to do so.I'd say it can be a good investment if it's something that your market can support, but in general think of it like a pool.

The interest will be more than half compared to HML, and they will be easily get approved. 

Is it expensive or comparable to normal capex reserve?

Staged homes spend half the time on the market compared to non-staged homes and they regularly sell for about 6% above the listed price. 

Like you I noticed that the properties were cheap compared to the rents and compared to other areas of PA.

It is usually a balance between owner and tenant.Most park owners DO have the authority to tell you what to do with your home and how it looks.

I suggest you run the numbers, if it's a cash-flow deal, look at the projected 3rd yr value and compare that to the last five years of market trends for the area. 

How high taxes are is relative, as people here complain, however compared to your neck of the woods they are a pittance.  

I'd says things like; "You are fixated on square footage determining if a house is comparable but you are comparing single story houses to my two story and single stories cost more to build and typically sell for more than two stories of equal square footage" and would get told "if you don't like it go to the review board".What's the bet that next year when we try to use comps from early 2019 when the market has been soft they won't accept them if the market has gotten stronger towards year end.

Here's an article where I compared both options:https://www.biggerpockets.com/blog/buy-rehab-turnk...There's no right or wrong answer, it's completely dependent on each investor what they want, their skills, etc.There's trade-offs for buying the turnkeys at retail price-- that isn't just for nothing.