As usual, I'm going to be a contrarian, please have patience with me.
First observation, for what it's worth, is that I've not been able to get a jib downhaul working thru the hanks. I've tried every hank, every other, I've used 1/8 inch line, I'm now using 2mm Robline Dyneema (great stuff). But it always jams, so I just run it outside the hanks and it works fine, doesn't get in the way at all. I think the problem with running it in the hanks is not that it gets caught in the hanks themselves, but inevitably you get loose bights of line between the hanks. Those get caught up on the OUTSIDE of the hanks and you get a jam. Having your jib stuck 1/2 way up teh forestay is no fun! Anyway, try it and see, your mileage may vary. There's really no advantage, though to running it inside the hanks. The jib won't "flake" any better than it does just pulling the sail down and bringing in the jib sheet to keep everything tight.
Next observation is that I set up a 2:1 reverse purchase downhaul. Details here:
https://forum.daysailer.org/forum/viewtopic.php?f=12&t=4274&p=20359&hilit=reverse+downhaul#p20342You'll need a double-block where your jib halyard meets the mast, and two bullet blocks at the stemhead, but it's a small investment. In return, you get a jib that goes down in a flash, one yank on the downhaul and it's down. Very useful during that last minute rush to the dock (I usually sail up to the dock). Also, the downhaul goes down your mast to a spare cleat, rather than cluttering up your foredeck, and you don't have to use any fairleads.
I did use the 2mm Robline for the RED line in the diagram, its' cheap - 36 cents a foot. I had to put a sleeve on both ends to tie a knot in it, but that's easy work - pretty sure I used a small barbecue skewer. For the GREEN line, I use some ultra-cheap polyester 1/8" line from Harbor Freight, something like $2 for 100 feet, my all purpose "boat string" for anything that doesn't take any real load (topping lift, some tie-downs). Anyway, I'm very happy with it, and once I took the downhaul out of the hanks, no jams at all. I leave the whole thing rigged on the boat, even when I take down the mast. The only thing that needs to be rigged/unrigged is fastening the end of the RED line to the end of the jib halyard - I have a bowline at the end and just put it into the halyard shackle when I'm hanking on the sail.
Good luck with your set up! Keep experimenting, it's fun.