I've got a camcart, some photos
here, and a
review in the reviews section. Though having just checked, the company seem to have disappeared so not a lot of help other than perhaps an idea of what to look for.
With the experience of mine I'd look for something as wide as your trike as the larger wheels give the camcart a highish centre of gravity - it has tipped over on a local very potholed road (admittedly it was piled high at the time on a trip to the tip).Curbs also have to be taken head on, though that may be more of issue for you on the trike anyway.
<nosey sod> Gareth - I'm curious how that towball is held on - bolted through a chainstay brace? The lock is in the way a bit. I like being able to secure trailer to bike idea. And what is that strip bolted on the side of the rack for? </nosey sod>