Your range riding hell bent is just about exactly right where I'd expect it to be. Very similar to what I've seen over years of riding a lot of different bikes.
But you can do lots better by slowing down. One thing that amazed me, was how much difference riding 18 mph vs 20 mph makes. But you should have 30 mile range just from slowing to about 25 mph. The stuff they talked about above helps as well. Pedaling continuously, once you slow to a speed where you can again, takes about 75-100 watts right off the top. So you can add 10-15% to your range right there. Then, having slowed down, you get better range.
If you have a ton of starts and stops, pedal hard getting going helps. A geared motor like a Mac will do better on stop and go than a DD hub motor too, in most cases.
The BEST way to learn to ride a lot more efficient, so you can stretch your range when you need to, is to have a power meter. Ideally, a really nice one like a Cycle analyst. But if your kit has a display with a simple power bars display, you can still learn to keep the bars off the max power level. With any kind of power being used display, you can then see the effect of pedaling, not pedaling, and how you use the throttle.
Then, you can correlate that to miles traveled. You'll then know, keep it on bar 3 instead of 5, I'll get 30 miles, or whatever. With the CA, even better. For me the magic number is 25 watt hours per mile. Hit that average over hills, even mountains, and I know my range will be as good as it gets without riding excessively slow.
