I also appear to have this problem. I remember a similar issue being reported some time back, to which there was a recommendation to minimize the UI scale.
(At 80%, the minimum, I can still only see a small fraction of the grid of the Deep Hold, and as mentioned, cannot place any items off the 'menu' area behind the grid, despite the grid being almost hilariously larger.)
I notice a different than standard UI color in your screenshots, is this relevant? The only mod I am using with yours is Bigger Bags, which I found FROM your description.
I would really like to be able to use your vehicles, but find myself unable to use a fraction of their potential with how few of your large vehicle modules I can fit in the fractional portion of the grid I can access. (If this is intentional, I apologize for bothering you.)