Get a Wing w/a Hannigan conversion and a raked front suspension. Then start with short rides and gradually increase the length and frequency of these rides.
To be blunt-you should practice (sitting still) collapsing forward on the bike and your wife reaching to the handle bars and the kill switch for the bike to bring it to a safe stop in case you become incapacitated given your health issues. Sorry, just being realistic.
Wife and I do that as I have had quad by-pass and am diabetic. She knows the kill switch and front brake. Once you and she have become confident doing this sitting still,
Find a large parking lot and practice this moving. This could mean the difference in both of you surviving you having an episode of some kind.
Don't be swayed-you only live once-go get that trike and enjoy.
Dawg