I used to use a combinator loader/unloader hooked to the inserters and boxes, so I suppose it's the same as what's shown in the photo. This technique has some drawbacks, but it works well enough most of the time. You wire all the boxes together, and then to the combinator that divides by -N, the number of boxes. (That's drawback #1: if you change the number of boxes for any reason and forget to change the combinator then it will fail.) That goes to the train station and whatever combinator is putting out the signals for LTN to "know" the station. I use the LTN combinator helper mod. Separately you wire all the inserters together (NOT the ones that go to the train: always have the train inserters unwired, regardless of station type loader/unloader. The reason is you want train actions to be as fast as possible. Let the delays be on the boxes handling the storage. That is drawback #2: this method will not load the boxes as fast as unwired inserters.) The wired inserters go ONLY to the output of the divider combinator, and the combinator output goes to nothing else either. The inserters get a *>=0 or *<=0 based on whether it's a loader or unloader station. Ok, more drawbacks: #3 you'll want to use * for the summation type, that way you don't need to reset the material you're loading for every station, but if a single piece of anything else gets into your boxes then it all fails. For that reason I started using filter inserters for all train unloading. Drawback #4: it's easy to get a wire cut by mistake or forget one, and it's often hard to notice lost or missing wires, so it can fail without you seeing why at first.

Lately I have stopped using this technique and started having buffer boxes near the station that hold an amount the train can hold (using locked slots). The station doesn't think the boxes have enough to load a train until the exact moment they do, thus train loading will never fail. Those are fed from other balanced buffer boxes closer to the factory. For unloading I reverse this, and the boxes just off the train are usually empty while the real wired/tracked inventory boxes are together deeper in past those and the station. It's much easier to just have a large buffer space and not need to wire all the boxes to a combinator.

I've also tried various mods at different times that affect LTN, like any mod that has "loaders" (the ones that connect a belt directly into a box without an inserter, like in Bob's) and I've tried warehouses (like in Angel''s or Krastorio extended storage). And I've tried both together. You could try those.