Hi Pete, wasn't baiting you, and I haven't read Joe Robinson's book, but I believe most people build their own XUL rods using 6' to 7' blanks, 2- to 4-wt.
Oh yeah, what Tom said...
I also agree an S-glass blank with a progressive dry fly taper would fish great here.
I would think as you push them out past 8', you could use 5- and 6-wt fly rod blanks with wide-lure-range result.
And if you never have the desire to throw 1/4-oz, stick to 3- and 4-wt.
Something else that stands out about these rods is the fish-turning butt on a progressive taper fly rod - the length and that butt give you the leverage on big fish.
The Japanese offer some in short lengths (down to 5') but, to me, it's the 7-1/2' to 8-1/2' rods that get my attention because of the reach they give me with light lures.
In my post that I linked, I mentioned that Yamaga Blanks identifies their 7-1/2' UL as "Stream".
Their 77 TZ/Nano flagship line, they identify as "River Light Game"
These rods move away from what people have come to expect with fast-tip spinning rods and, especially fighting fish, behave like the fly rod tapers they, in fact, are.
Also not unusual to see people casting these with a working leader almost the length of the rod, and loading the rod exactly like a fly rod before they shoot line.
I believe Joe R gave that cast a name, but never read the book.
Here's the Light Game catalog from Plat, my favorite Japan vendor: https://www.plat.co.jp/shop/catalog/def ... -game.html
Here are load curves for Yamaga Blanks newest series, 5'3" to 8-1/2'
(note the /B models are built as baitcasters)
also note, Yamaga rods are next to impossible to get - you have to get in the production queue with a deposit, and the handfuls of rods that are delivered for retail literally sell out in hours.
If you think about all the venerable spin/fly outfits, they were short para 7-wt with big-loop guides and an ML spinning rod.
Here, you could use single-foot guides and build a nice XUL/fly combo with "Tennessee" cork + rings, that would be a decent light-line fly rod.