The paper size guide you are referring to is only for the NEW Loop Bands and it only goes to "Size 12" which is about 8"
The standard Apple Sport Band Extra Large goes to 245mm which is 9.65" - this might be an option for you? It comes in all kinds of colors. Also take a look at other bands on the site besides the Loop Bands.
The Link Band while expensive has the ability to purchase an extension kit and add to the band. It is a very very well made band and I have used mine since the 1st Apple Watch came out.
44mm-black-sport-band-m-l-l-xl
Keep in mind you can order from Apple, try it out to see if it fits and if not return within the first 14 days at no cost to you. They make it very easy to get what you want.