Well, it’s hard to give you precise solution to your problem, but I’m pretty sure it’s possible.
You need to rework your book generator and avoid to create a curve line , but rater probably instance a line into a point, or generate the book from a curve/line.
Setting a line length is quite easy, you can generate a line of size 1 and scale it to any size you want after that.
I made a book generator myself if you want to have a quick look :
It was super complicated to get that particular arrangement, but anything else was pretty straightforward.
The main takeaway is that there are many roads to a solution, but it can quickly become complex too.
Of course, using loops makes things much simpler in many cases, but it’s also generally very possible to get to a result without !
Good luck !