Is it possible/within reason to manage your own property while living so far away AND working a full-time job?

They are probably not going to admit over billing and refund us any money.In the future, how do we make sure their bills are reasonable and honest?

It depends on what the reason you have for selling is @Jacob Beirwagen.

Is there any reasoning behind $200 a door?

There's no exact science to it but like you said it's only usable about half the year (due to temperature, I presume) and then even when the weather is warm, it could be raining, so truly only available likely somewhat less than half the year - maybe an extra $0.15 - $0.20 psf/mo added to the $1 psf/mo sounds reasonable.

One of the reasons I used them is for their flexibility in what they consider cash reserves (which you need a lot of when you have 7 or more properties....Per Fannie Mae: 6% of the aggregate UPB if the borrower has seven to ten financed properties (DU only). ). 

The reason you hear so many horror stories about PM is because Landlords fail to research and screen.

Well @Jason Graves, Personally i wouldn't pay for asset management, that would be my roll. of course if for some reason you don't have 2-4 hours a week to deal with it then perhaps you could out source it.  

Lender states our insurance is inadequate, my agent tells me their requests are not reasonable or possible for most insurers, yet their company has a preferred insurance agent who can write the correct policy... fishy.

If you intend to occupy the larger unit and make that the reason for eviction, you may mitigate some of those issues.