Simplify a horizontal scroll animation with code

Hi, I am working on a site with a horizontal scroll section with boxes that cascade over each other as the user scrolls. At the moment the only way I found to do this in motion.page was with quite a complex timeline. I wonder if there is a simpler way to do it with a custom GSAP code. Or can anyone suggest any other way to achieve it? You can see it in the itinerary section here:
https://themongoliatour.com/tours/gobi-tracks/

and attached is my current MP set up which is for only 7 days but I have other tours to create with 20-30 days.

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