Before I bought my first recumbent I'd often thought about learning to ride one. I had just a generic idea of a "recumbent" being a low slung bike with a supportive seat, and all being much of a muchness. At that time I had no real idea of the differences between different types, and had an idea of vintage ones from the 1930s with a longish wheelbase and some kind of remote steering. As I got nearer the point where I might actually buy one, I began to scan sites such as
ebay and realised that while no two were really alike, there were certain distinct categories such as short wheelbase, long wheelbase, front wheel drive, under seat steering, over seat steering, lightweight unsuspended, heavier with suspension, obvious sporty bikes, and others more geared for luggage carrying. A baffling choice, and I hadn't even considered trikes at that time.
The months went by, and nothing turned up within travelling distance to even have a look, let alone a test ride. I had a vague hope that I'd find something that would cope with my modest road use, less extreme bridleways, rail trails, maintained towpaths and what have you, similarly to my steel tourer, but without the aches and pains that longer trips were beginning to cause me.
At that time I wasn't yet aware how even more difficult it could be to get a match for your needs with a recumbent compared with a diamond framed bike, let alone a physical fit if you were taller or shorter than Mr or Ms average. It wasn't just about seat height. So my recumbent aspirations could have come to a grinding halt if I hadn't bought the one that fate put in my way which just happened to have a wide range of adjustability (not common in recumbents), was cheap enough to take a punt on, and was within lockdown travelling distance.
It all turned out well, I learned to ride it, experienced the sensation of flying at low level on 2 wheels, and it was a rolling restoration and test bed for continuous improvements, some successful, some not. I've learnt a lot about recumbents in the last 3 and a bit years. Fortunately, I can't leave things alone, and like to tweak and experiment. So pretty much more than any other bike I've owned, it was the right bike at the right time for me. It is a vintage Iowa LWB Linear. If the OP wants to read my experiences on learning to ride the beast just search for "Confessions of a Recumbent Virgin" here on CC or even just "Confessions" might do it.
I wouldn't have known any of that from just sitting on it, it takes some time to find out things like that, but if the OP can find a recumbent or two to sit on and look at it can help to eliminate some from a potentially long list.
It does pretty much everything I want apart from fit on public transport or bike racks, otherwise it's as
@Anthony-C says.
For some time I thought a Streetmachine might be my next bike until I had the chance to sit on one, and found myself teetering on tiptoes.
Maybe OK on tarmac, but definitely need to be able to flatfoot it if riding uneven surfaces off the beaten track.
Once the OP has managed to acquire a recumbent bike, he shouldn't be surprised to find that there will be a magnetic force which causes more recumbents to accumulate. The first one is the most difficult! Even I managed to acquire a trike, even though I'm more of a two wheel person.
As for recumbent trikes, most people can hop on a trike and ride it as long as it fits but if you're used to two wheels riding on a camber when you're going straight on, or experiencing G forces when cornering, or being rocked from side to side on an uneven road can be disconcerting.
It takes a bit of time to get used to the different sensations. It's probably easier if you've never ridden a two wheeler.
The width issue might be solved with some tadpole trikes being sold as NT or Narrow Track to improve the access through doors, gates, etc.
My Delta trike shown below posing at an A frame barrier has a width at the widest point of 740mm/29 inches. There is clearance all round. The sides of these are pretty standard but the width can vary at the whim of whoever installed them, and if the approach isn't straight it complicates things.
It will go through kissing gates but some are tighter than others and it sometimes has to go up on its back wheels to get through. It's easier to get the Linear through on its rear wheel in those cases despite its extra length.
It came through that one on its back wheel. A short wheelbase recumbent bike, being only slightly longer than a conventional bike, would probably get through on its wheels. For most barriers, where there's a will there's a way, but some are just impossible unless you're in a group.
The Linear, and more recently the HP Velotechnik Spirit which I'm currently evaluating, tend to go further afield than the trike but as the Linear is marginally wider across the bars than the trike is across the rear wheels it would be reasonable to assume that anywhere the Linear could go, a trike of similar track width could go too. A tadpole trike might give more confidence as you can see where the canalside wheel is going on a narrow towpath for example but this particular Delta trike has dual wheel drive which is useful for traction if the surface deteriorates.
Having a plan B is useful if a problem occurs when you are expanding your range and having a short wheelbase two wheeler makes it easier to get a train home if necessary, or even a planned train out/ride home trip. Just something to think about while looking at recumbents.
As mentioned by previous posters, local knowledge is the key to knowing what access is feasible and what's not, as is whether the stretch of canal path you're hoping to ride on is an immaculately surfaced dream or a mountain biker's challenge.