I know the kind of thing you are taking about Trike Lady, and that style is available over here too. The Trike Shop make their own back ends to suit the bike they are triking. For me I need the more open style as I need to put the rear wheel in between my wheelchair wheels. That allows me to get close enough to lift onto the riders seat, grab the handlebars and haul my ass up and onto the seat. Getting off is just the reverse of course. Here are some examples to look at.

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