So what kind of riding is this, in this remote beach area? Are you cruising an endless beach? Climbing a mountain on the island? I'm assuming this is not a paved bike trail here at this point. Is there any kind of trail at all?
I guess what I am trying to say, is like a full size motorcycle or car doesn't belong in some places, there are actually some places not so suited to ebikes, unless they are very specialized to handle the terrain. In an extreme example, while you could ride a bike to Everest base camp, its more a trail suited for walking to that spot. You get into an equation of whether its better to lug the extra weight of a 15 pound motor, and 10 pound battery, or just walk it. If its that tough to pedal this place, you will need more than a small wheel, weak motor, tiny battery folding bike to ride it. If its cruising the beach, then you want a 20 inch wheel fat bike. You will want a fat tire more than the folding, though you may have to carry the thing taken apart. And btw,, how do you get there? You can't hop on a plane with very big batteries.
We give really shitty advice here, without enough information, as my previous post showed.