I've never seen a trailer here in Australia with a removable hitch, possibly not even legal which may explain it. The 2t one would work for you as it can be mounted with two bolts down the center line of the hitch. Most of our trailers also use an A frame (to allow the handbrake to mount using the two rear bolts), my army trailer is one of the few that has a single center tube so I had to work around that as well.
You could always mount a plate on top of the tube and hang it over the front and then brace from underneath (end of tube to underside center of the plate) so it is slightly skinnier and allows the bolts to drop in.
This is what I did, made the 'L' bracket that bolts to the tube.
Cheers
Steve