I have a 2003 trailer. Around 2015 Kendon changed the design of the center rails and chock so that front tires would fit between the rails instead of slightly riding up on them. Also lowered the chock for easier in and out and made it adjustable for different wheel sizes. Upgrade is available on Kendon website and is a pretty straightforward installation. I paid about $200 a couple of years ago.
Nope, that's not what I am talking about. As I said, around 2015 they changed the design of the rails and chock on the single (and double) trailer so the front tire will fit between the rails instead of tending to ride up on them, twisting the steering a bit. It is available as a replacement part from Kendon.
I was looking at the Baxley trailers and the Ramp free trailers a while back, they both look like nice units. A little larger the the Kendon units but like you said not sure what kind of dealer network they have. I have contacted both and they are pretty much custom build with each having a couple of designs for Trike, Dual Bike trailers or single bike trailers. Everyonce in a while you will see a used trailer on Cycle Trader. Have seen all the brands listed on CT.