Stop Acrobat from padding the width of a narrow pdf page?

[Parris37]

I'm creating  pdf ebooks from series of jpeg image files of each book page, using Acrobat XI's "Combine files in Acrobat" context command in Windows 10. All works fine, except I like to add the spine of each book as a page in the ebook. These spines are often less than than an inch thick, perhaps 1/2" wide physically. When Acrobat produces the pdf the page of the spine is automatically padded on left and right to 1" width. I can later use the cropping tool and remove this padding, but can I get Acrobat to create the pages of narrow spines without padding those pages in the first place? (I'm scanning the pages at 300 dpi, and if the spine jpeg is less than 300 dpi wide, Acrobat will consistently pad it to 300 dpi wide, or 1" according to the ruler in Acrobat, adding white equally to left and right sides.)

[Test Screen Name]

The minimum page size is one inch (25.4mm). A pity, but there it is.

[Parris37]

Is this defined in the pdf standard, or is it an Acrobat-defined minimum?

[Test Screen Name]

Acrobat. Similarly max 200 inches is Acrobat.  That limit was increased with Acrobat 4.0.