I respect all opinions, but battery meters and power surveys? Never had any need or desire. I do use an accurate voltage meter. It tells me all I need to know. You can turn this all into a science project, but it is really basic stuff. You already know what uses the power in your camping lifestyle, and it isn't hard to figure out what stuff draws.
For the OP, you have to figure out what you cannot live without, before you can figure out what you will need. My family gets by with the minimum. We came from tent camping to where we are now, so it was a no-brainer stuff to us. No electric coffee pots. No hair dryers. No electric toasters. Definitely no A/C or microwave. One of the luxuries we sometimes use is the microwave, and we simply fire up the genny if we want that. Same with A/C, but mainly we choose to not boondock where A/C would be required. None of this is right or wrong, it is just decisions that you have to make.
Just last weekend I installed an inverter, dedicated to the TV. What a luxury! I guess I am in danger of losing my minimalist cred.
Managing power to us means planning to run the generator for charging, while we take showers or do dishes. The water pump is the largest use of DC, second only to the HV system. Might as well run it while the converter is putting out a strong 14+ volts. The water flow is better too, so a side benefit.
We've got solar charging now, but I'm approaching your question from the perspective of not having it. Because it is out of the question given the $500 budget target.