July 2018 edit: see the version 2 hitch idea I came up with here: https://www.instructables.com/id/Burley-Travoy-Qui...
I wanted to make more hitches, and didn't feel like buying more of the original Burley Travoy hitch in order to modify them, so I came up with a new arrangement. It's under $20, and very sturdy.
Use at your own risk!
Here's a simple Instructable that shows you how to convert the Burley Travoy trailer hitch into a quick-release hitch. It already has a quick-release mechanism for attaching and detaching the trailer, but the hitch itself is made to be bolted onto a seatpost rather permanently (although securely). It requires tools, fully removing one bolt, and substantially loosening the other bolt, in order to detach it from a seatpost. This makes it impractical for use with bike shares, such as Divvy bikes in Chicago, Citi Bikes in New York, etc. This modification integrates a quick-release clamp from Minoura with the Travoy hitch from Burley.
The Instructable is more about the idea and sourcing the right clamp, but I've included some additional suggestions about how it can all come together. If you have any questions, feel free to ask.
Use at your own risk!
The clamp from Minoura was obviously made for a water bottle. Even though it's aluminum and seems very strong, I suppose it might not hold up to the stresses induced by a fully-loaded Travoy. I think it will, but I'm no expert. Maybe you'd want to add a safety strap, so if the clamp attachment breaks, the trailer will stay attached to the seatpost. They have these on other bike trailers, but I'm not sure why Burley didn't include one for this trailer. I think I'm going to add one.
Who knows, maybe Burley will be inspired to sell their own quick-release clamp hitch. They can be made durable enough for the quick-release rear racks that are out there, so the engineering is possible, but this is the best I could figure out with off-the-shelf components.
Step 1: Materials Needed:
1. Burley Travoy hitch. If you have a Travoy, the seat post hitch was included with your trailer. If you need another, they're available from Burley, and on Amazon last time I checked.
2. Minoura Quick Release Bottle Cage Holder. Oversized. BH-100C-M. This is the bigger clamp that will fit around a seat post, and has two mounting screws. See: http://www.minoura.jp/english/accessory-e/bh100c-e...
3. A scrap piece of aluminum or other metal. Mine was about 3mm thick, which I think is probably the minimum you'd want to use.
4. A drill and drill bits.
Optional but preferred:
5. A metric thread tapping set.
6. A punch (see picture)
7. A hammer
Step 2: Removing Bits
Remove the two main screws from the Travoy hitch to release the curved back plate.
If attached, remove the two screws from the Minoura clamp to release the water bottle cage holder. When mine arrived they were separated already, so I only needed to remove the two screws from the clamp.
Step 3: Align and Drill
Align and drill holes in your scrap metal.
My piece came with two holes that lined up with the holes on the Travoy hitch already. To get the spacing for the two holes that align with the Minoura clamp, I took a pencil rubbing. See the picture.
Use the punch and hammer to mark where your holes need to be on the metal. It will keep the drill bit from dancing around - the bit will stay in the dent formed by the punch, and allow you to drill straight through.
I decided to thread my scrap metal to match the screws. This might not be strictly necessary, but that's how the curved back plate on the Travoy hitch was done, and I thought it was a good idea. If you'd rather not invest in a tap set, you might get away with 7mm nuts for the Travoy hitch bolts, and good locking washers for the Minoura clamp. Come to think of it, locking washers are a good idea anyhow. I'll probably add those later.
If you'll tap threads, you use the matching drill bits as described in the next step. If you use regular drill bits, use one that's the same size as the bolts, not smaller and not very much bigger. I didn't measure, since I tapped threads, but they're going to be around 5mm and 7mm in diameter.
Step 4: Tap Threads
If you decide to tap threads on your metal plate, you'll use the 5mm tap and matching drill bit shown on the tap set for the holes that receive the Minoura clamp screws, and the 7mm tap and matching drill bit for the holes that receive the Burley Travoy hitch screws.
Step 5: Attach
Allen wrenches are needed for screwing it all together
Step 6: The Finished Product
Here are a few views of the finished product, from the top, side, and bottom.
This is my first Instructable, so sorry for the lack of intermediate pictures. I didn't think about doing an Instructable when I started, so I didn't take pictures until the end. I happened to have a bunch of identical scrap aluminum pieces, so I was able to show one that had only the three holes in it.
On my first try with the holes, I didn't get good alignment with the Minoura clamp holes, so I ended up doing the pencil rubbing for the second try. I think I got really lucky on the second try, because everything lined up perfectly. There's not much room for error because the threads have to align very closely, so it's probably a good idea to have extra scrap metal available, and a lot of patience!
I haven't tried the clamp out yet, since it's super hot in Chicago today and I don't feel like pulling around a trailer, but I can tell from the way the clamp attaches to the seat post (see picture) that the alignment's going to be perfect. Maybe I'll supplement with a another picture with the trailer attached at a later time.