I was kinda surprised to see that you got a trike. I guess that's what shops stock these days, so you were just getting what was available. Sure the trike is low. I don't get why lowracers are too low but trikes that are just as low are OK. If it's any help, I've been riding lowracers for almost 20 years and I don't feel 'invisible' due to my height. OTOH most of my riding is done on country roads, not downtown rush hour. Ride to be seen and you'll be OK.
If that seat still hurts you, it seems like regular chairs would hurt you too. Can you add extra padding? Or as an experiment, take padding away?