I'd start prowling Craigslist. They pop up from time to time.
The tadpoles do sit mighty low. The Deltas, a little higher.
I can do essentially a full hands-free squat. So, getting up and out of stuff is easy, at least when healthy.
I have friends that have major flexibility issues, and difficulties getting up out of a chair. The Tadpoles are just too low. Perhaps a Delta?
Our local co-op manager, Juan has bad Parkinson's disease, and has built a custom delta trike which works well for him, with the little higher seat.
I've thought about making my own design of a tadpole, using a pair of real forks up front, and try to figure out locking brakes, perhaps a wheelchair style brake. That way, one could use the downtubes for grip and support.
I could try to light a fire under my design and building. 3 months?
As far as steering, I find they tend to steer ok, although sometimes a bit squirrelly on steep descents. Nothing extreme with efforts. I've also had them fell a little squirrelly on hard braking.
You might also consider E-Trikes???
Whew, they're not cheap. DIY conversion?
What is your storage like? Do you have a garage with flat space that you can roll into?