Maybe, and yes. Maybe you can ride in some soft sand, but you are going to put a ton of heat into the motor and controller if you do extended riding under very heavy loading. Possibly to the point of burning something up. You don't say how much you weigh, that will make a huge difference. I have no idea what Longboat Key is like. Hope there aren't a lot of dunes or steep grades to climb. Do you need to let air out? It's best but you don't have to. By letting air out you will also increase drag on wet packed sand or pavement riding. Most people forget that eBikes are electric assist, not electrically powered. They don't work like a motorcycle, unless you put a giant motor and equal battery.