Sometimes the fear of something such as heel strike can be more limiting than the actual occurrence. There are a lot of SWB recumbents where it doesn't happen, and there are plenty where it does, and riders just learn to adapt by splaying their heels out or pushing the pedals round in a partial circle in tight turns, until it's not an issue any more. If in doubt, while doing a u turn you can always Fred Flintstone it and paddle round using your feet. You've got a high bottom bracket, so getting confidence to keep your feet up as much as possible helps, as it's pain to be stopping and starting , and having to get your feet up and down from there any more than you have to. With practice, you ought to eventually almost be able to do trackstands and get going again without putting your feet down.
Looking at pictures of the J bars, there's loads of adjustment. I found when first I tried cockpit style bars that there was a lot of tiller effect as the grips were a long way behind the steering axis. That meant that the bars swung a lot for a small amount of wheel movement and made tight turns difficult as the bars hit my legs. The solution in my case was to turn the stem round. This brought the grips forward, closer to the steering axis meaning that the bars didn't swing so much in tight turns giving more room for my legs, and it felt more stable. I don't know if you are in the same situation but maybe adjusting the bars so the grips are closer the steering axis might give more legroom. The Schlitter probably has way different geometry to the bikes I ride but I would think that the thought of the bars contacting your legs unexpectedly while trying to turn is just as much a confidence sapping thing as it was for me. You might not be able to get rid of it entirely but reducing it would help a lot.
When I started riding recumbents there always seemed to be a gap between launching and reaching 4-5 mph, where I felt unstable and wobbled. I came to realise that if I kept going, it would become more stable as the speed increased. It was counter intuitive, as I originally feared that if I speeded up I'd just be going faster when I fell off. My first ride had me riding along a road, avoiding junctions or anything that would cause me to change speed or direction in case I wobbled and fell off. It was scary but amazing at the same time. It took a while to realise that if you relaxed the death grip on the bars, the bike would take care of itself. It's hard to relax while riding something so strange and different, but that's what you have to do. It took a while, but I learned to ride to a standstill before putting my feet down, and slow riding is really relaxing.
Starting uphill is just something that you do now. I remember getting really anxious at a local uphill traffic light, getting across busy junctions, stopping and starting in traffic. It's just something that you do, and traffic that I thought was getting in a queue to flatten me one by one actually gives masses of space as they don't know what to make of a recumbent. There were times when I sat by the roadside almost frozen by anxiety, delaying launching. I found that it's too easy to get into a state where you over think things. I learned that whatever your doubts and doom laden imaginings, Just Do It. What's the worst that can happen? I've only fallen off once, unfortunately into a handy patch of nettles, off road when I hadn't yet got the hang of the gearing, and stalled on a steep hill.
It's just practice and perseverance, and although there may be setbacks along the way, the next ride will always be different.
