I see a thread about adding a third bow by sourcing the bow from an old kayline. Is that what you did? Or did you fab something?
IIRC I fabbed something using an old CJ-5 bow I had lying around for a middle bow before I got my full cage.
Now I just have a stubby little ~5" bow that bolts to the top of my full cage. I made it by modifying a short bow setup that came with a now-discontinued full bikini top for an LJ. It was made to bolt to to the rear diagonals of the stock LJ cage to hold up the back end of the top. (Actually, that's the full bikini top that I now run, it sits on top of my full cage, but I got it years ago right before they discontinued that model
)
There's really not much to figuring out a third bow, pretty much any CJ soft top bow you find will be too long, so you'll be able to cut it down to what you need. The issues are:
1) figuring out a strap or rod setup to hold it in place so it doesn't fold forward or back. I think I used two simple black nylon webbing straps, one going to the bow in front and one going to the bow in the rear. I don't recall exactly how Jake did his in the thread I think you're referring to. I remember thinking a couple pieces of all-thread and holes in the bows could be used as well and would lend some adjustment.
2) mounting the bow at the bottom. I can't really recall what I did, I think it may have actually fit between the ends of other two bows in the Tigertop bracket on the tub. I seem to remember just having to pinch the bottom of the tube a bit to get it to slide in and drilling a hole to use with another one of the pins. I'm pretty certain I didn't end up having to use an extra bracket or anything on the tub rail because I know there's just the one set of holes for my soft top bracket.
You can get it where the extra bow isn't super hard/tight to get up and then add a piece of pipe insulation on top of it to tighten it up and have some cushion for the top fabric.