I'm planning on making a shoe rack/bench, and have been trying to figure out the best approach to cutting the corners on these 46" wide shelves:

I've made something similar in the past, and cut out the corners with a jigsaw, but I was not happy with the results. I now have a table saw and handheld router, but can't figure out a way to make these cuts consistently.

I haven't attempted it, but I'm pretty sure that using a dado stack on my table saw is not feasible with something this long.

Another idea I had would be to clamp up the bottom two shelves and use a straight cut router bit with a guide – but consistency might be a challenge?

Is there another approach that would make sense for this?