Are bicyle passenger trailers limited to child sizes? I have looked for larger sizes but most stores only offer trailers sized for children. It would be an inline trailer sized for a small to medium size female, 160 pounds (72kg) or less.
Equinox makes a larger version of a child carrier for passengers up to 200 lbs. See: http://www.equinoxtrailers.com/store/item/19
Wike trailers makes a Special Needs trailer: http://www.wicycle.com/special_needs_extra_large_bicycle_trailer.php
Pashley used to do something a bit like this that I thought went to adult sizes: http://www.cyclesense.co.uk/m17b0s435p7209/MISSION-Piggy-back-Mk11-special-needs-24-inch-wheel-2012 (And that might be big enough for you.)
Looking at http://www.castlecaremobility.com/pashleyaccessories2.htm maybe the Pashley was only child size anyway.
I've never seen a large equivalent of the sort of trailers that small children just sit in though.
If by "inline", you mean a single wheel trailer like the Bob Yak, I've never seen a passenger version of them, only two-wheeled.