Okay on the Not DIY sort! Some it works and others it is a big bore so we need to go the way that works for us, not what some guy on the internet suggests!!!!
And that can also fit on choosing fish as fish do vary, just as people often do. Some seem to be born rowdy,some not, so I tend to go with the general ideas of what fish may do but not totally write off a favored fish just on what they might do. Algae eaters are not one that I find to be a problem even after several years, so I might tend to go with them and look at them more like temporary roomies, rather than long term partners. My fish stay as long as they are agreeable and leave very quickly is they become too much trouble. Roomies, not a wife? I would shy from roomies who might eat the other roomies, though.
That size tank can give a lot more opportunity for things to work as we can also do more to set the tank to favor each group. You've noted how the loaches tend to "disappear" and that can be used to advantage when setting the decor and choosing other fish as many fish do have a preferred space where they spend more of their time, so if we want a fish who likes to hang out near or under a rock, it may be that there is no conflict at all with a group who likes to hang out up high and school together.
I recommend watching how each fish behaves and try to spot how they might like to live. Kind of like there are some city folks who do the condo/apartment thing while others want a yard or not even to see a neighbor!
But I do keep in mind that I'm bigger than they are and I get to choose who stays and who goes.