Tabs in tabs. Is this okay and if not how do I fix it?

I'm designing an app that handles the majority of the math and bookkeeping for a tabletop RPG that my friends are designing. The "character sheet" is fairly extensive and we REALLY wanted to avoid scrolling, so to divide up the information I have two sets of tabs - horizontal for the broader categories and vertical for pages within it. Here's a couple examples:

There are a few issues with the designs that I'm working on but right now I'm focused on the tab layout. Vertical space is precious and I think it would be confusing to put two sets of tabs on top of each other anyways, so I came up with this. To interact, side swipes will change the horizontal tab, while vertical scrolling is for lists so the vertical tabs need to be touched.

I'm not entirely satisfied with it, and many people say tab nesting is bad design. I need some input!!