After a search that began with this thread (link), my Vietnamese wife and I finally found exactly what we needed:
Modern 3-Bedroom 4-bathroom 3-level house with partial furniture and air inverters (modern air conditioning) and huge kitchen, in the same neighborhood where I survived monsoon season from November 2018 thru January 2019.
₫10,000,000 VNĐ per month on 1 year contract, 1 month deposit, first 6 months rent paid in advance; very common for 1 year leases in this town for both locals & foreigners.
We didn't attempt to negotiate those terms as we like paying ahead & not worrying about rent for a bit.
I grew up near the shores (between the bay & the ocean) in San Diego, so sun or rain, I like to be near the water, and I'd much rather be living here in the Thanh Khê Tây neighborhood, Thanh Khê District (Google Maps link) than at Mỹ Khê Beach (where I first swam in 1972) & the An Thường tourist ghetto where I've already lived a few different times.
The cost of living is much more reasonable here at the bay (₫10,000 bánh mì & cokes are the norm) with virtually zero English signage...and frankly, I didn't come back to Vietnam to regularly socialize with foreign tourists.
I picked this part of the bay shore line because when you move east and closer to the mouth of the Hàn River, the bay water becomes decidedly murkier.
The more you head Northwest, the bay water becomes even more pristine, but this location gives better access to the city without living in most crowded and busiest parts.
We definitely got lucky on the place we found because we discovered that when you are seriously looking for a house outside of the tourist areas here, it's quite common to find 3 or 4 bedroom places listed between ₫8 and ₫12 million VNĐ, but they end up having no air conditioning installed and usually less than suitable furniture (frequently one or more bedrooms won't have a bed) with smaller kitchens and over-crowded neighborhoods.
The Vietnamese owner of our property lives in the United States, and she's been having very poor luck keeping any good tenants.
She's really happy to know that it's going to be an American and a Vietnamese woman living here and she's especially thrilled that it might be for the next 4 years while our daughters study at the University.
She is agreeing to support us with one additional new air conditioner in the one room that was lacking it.
She's even holding the place for us until October 1st, something that would have been unthinkable in the foreigner friendly areas.
So if someone is reading this and hopes to find something similar in this city in the foreigner-friendly neighborhoods, it's possible to find it, but the price will likely be in the ₫14 - ₫22 million range.
Nice 2 bedroom apartments are easier to locate, the better ones running between about ₫12 to ₫18 million, but you can definitely find a no-frills place for ₫8 to ₫10 million and studios & small 1 bedrooms from about ₫6 to 8 million.
If you can live without air conditioning or an elevator you could even get something liveable for about ₫5 million.
it's also possible to deal directly with landlords if you post in Tiếng Việt on Vietnamese Face.book group pages, but we found this place through a listing on an agent's profile, and we don't have any qualms about having to pay 1 million more than it might have been without him.
Good luck to anybody who is searching in this city for long-term accommodations.