You are thinking too much!
My HF antenna is like this. Some wire hang about 3 meters high from ground from a tree to house. About 30 meters long. At one end, I have a coax, RG58, I think. Center pin goes to the antenna. Braid goes to ground rod. Coax is about 10 meters long and goes into my lab. There, I just connect it to a proper connector and into a radio.
It works surprising well. The impedance is all over the place, so I do not transmit on it, but for receive, it's great.
Balun is only needed when you have a coax and antenna is symmetrical. Or, when you know the impedance and you have to change it. In this time of Long wire/random wire antennas, and dealing with wide frequency ranges, matching is not possible with balun. You will need an antenna coupler.
For receive only purpose, I wouldn't bother.