Well, some re-seller had a Tomos Trike mod...and a couple of the larger ones could carry a (folded) wheelchair in the back basket, and also, there is the Honda Gyro (http://www.hondagryo.com) the Gyro-UP model looks like it'll do.
I have some experience with mounting the electrical engine system from a Lark personal mobility scooter to one of these trikes as well, with an alternator system that charges the standard U1 class battery, so you got both gas and electrical power available.
That's a handy mod too, cause with a large chain shop like Meires or Walmart, you can roll up on gas, switch to electric and go right on in.....and switch back to gas one the way home and let the alternator charge the battery for ya.
Lemme know if ya need a hand with somethin like this.
-Ree