Yeah, ride slower, pump up those tires, use 300w but pedal up 100w of it. A more aero bike would be best of course, but to max your range on what you have ride 15 mph. Its quite astonishing how much more wind resistance there is at 20 mph, vs 15 mph. And simple stuff, like don't ride with a big winter coat unzipped. Take it off when it gets warm. Don't make your wind resistance bigger with a huge hat, or baggy clothes. Dress slick.
Sounds too slow, but in fact you can cover 75 miles in a 5 hour ride, at 15 mph. About the length of time most people can stand at most, in the saddle per day. 200w average, for 5 hours, thats a 1000 wh pack.
Catch 22,, a 52v 20 ah, 1000wh pack won't deliver out 1000wh in the real world. A few weaker than spec cells, internal heating of the pack sucks a few wh, and of course the thing is new for only a few weeks.
But you can go 75 miles on two, 52v 15 ah packs. And that is not too bad for carrying it, if you have a set of panniers on the bike, or a back pack. Run one pack then the other if that works best for carrying it.
As for charging it later, it depends on the town. My medium size city has almost zero free range plugs. In parks, they are switched off unless you get the permit and pay a fee for your party. New buildings have no plugs. There used to be plugs at walmart, but they removed them. A store with an ice cooler out front remains the best bet. But there is a limit to the power you can pull from a 20 amp plug that has a big ass freezer running on it. So a big charger if it works, but maybe carry a 250w too.
In the smaller towns that aren't over run with homeless, I find plugs that work in city parks, community centers, etc. I have also camped in state parks that have electric plugs in the camp sites. Cheap here, but pricy in other places.
Lastly, look for vacant houses. That real estate sign out front usually means the lights are on inside.