As with all things you can make it as simple or elaborate a system as you think you need and the cost of which can be cheap or very expensive and the install can take minutes or hours
But either way they all pretty well do the same job. As you can imagine we have people here with systems that cover the whole spectrum.
What you have posted looks to cover both the solar controller and battery monitor needs -which is sweet but you will need to watch that when you buy your solar panels that the controller meets the output. It might also take a little more work to come up with a place to mount it than a simpler system. You could solve your current issues by purchasing a different battery monitor that does what you need for under $20. I use a small one thats simple mounted with double sided tape beside the 12V plug in the trailer. I plug it in only when actually needed. Its easy to read and shows the actual state of the battery & it beeps if the battery drops to 40% - paid less than $15 for it. It pretty well tells me all I need to really know.
In regards to my solar I have a pretty simple system - a small solar controller which came with my solar panels is always attached to the battery and enclosed in a small water tight box attached to the battery box. I think it only has two lights
on it - indicating charging & fully charged - the battery monitor tells the rest of the story. Simple, cheap set up but it does the job and has worked well for a number of years now.
Bottom line it really comes down to what you really think you want or got to have and how deep your pockets are.