I posted this in another thread but I wanted to make it easily searchable plus I am also going a bit more in-depth with the features and why this works best for me. The pics and instruction for easiest install of a LeatherLyke locking trunk with back rest.
First, it's a 35qt 17" Wide x 12.5" Tall x 18" Long locking trunk, Its nearly water proof (the company suggest using it as a cooler although good luck draining it, it doesn't let in rain because of a gasket around the lid and comes with plugs to fill in the unused mounting holes.), has 2 tabs on the back for hanging helmets that are inaccessible when locked so helmets are secure and my wife likes the back rest over the OEM backrest although they do come without the backrest (BTW lightly used OEM backrest for sale). You can get it with the tassels and chrome studs or with no tassels and minimal black studs.
I replaced the supplied 1/4-20 Carriage bolts with 1/4-20 socket head cap screws and washers, this is because there is no place for the square on the Carriage bolt to locate. Also I'm a machinest so the quality of the hole placement annoys me being as they use 1/4 inch bolts and drilled all the holes 1/4 dia but they dont quite match up.
First install the OEM Rear carrier attachment kit and the Rear carrier. I wont post instructions to do it but you can find them on Honda's site.
Next were going to open up the holes in both of the brackets and the holes were going to use to mount with to .277 or a letter J size drill. Also we need to trim off about 1/4 inch off either end of one bracket, this is because the rear carrier tapers a bit and the welded on studs get in the way..
Here I put the bolts into the holes and placed it on top of the rest, notice the front (further away) bolts don't quite sit straight, I guess depending on your luck you may need to deal with that as when I originally mounted the trunk I used the other 4 holes and it worked fine but it sat too far back for the Lady so I'm mounting it further forward, anyway we will fix that in a sec.
Go ahead and add the trimmed bracket then the lock washer and nut (I'm tempted to swap in a self locking nut.) tightening them just enough that you can still adjust the trunk.
Once in place I used a 1/4" endmill and a power drill to open both of the other holes in the trunk and to open up one hole in the bracket so they are more of a short slot.
Add the other bracket, washers and nuts and tighten them all securely.
Here is the finished product except this is when I had it installed on the other holes so it will sit 2-3" further forward.
Hope this helps for those looking for options. If you have any questions feel free to ask or PM me. Later this year when I finish paying the bike off or early next year when my taxes come back I will look into possibly installing LeatherLyke hard locking saddle bags, they just dont have a set for our bikes so i will need to see about how to get them to mount using OEM stays. I may need to make an adapter.
